Disposable absorbent article combining low viscosity liquid handling and high viscosity liquid handling

ABSTRACT

The present invention provides a disposable absorbent article which combines acquisition performance for low viscosity liquids such as urine with acquisition performance for high viscosity-liquids such as faeces in its front region as well as in its back region. The topsheet wetness of the disposable absorbent article of the present invention is less than 300 mg. The front region storage under pressure of the absorbent article of the present invention is more than 800 grams per square meter.

1. FIELD OF THE INVENTION

The present invention relates to absorbent articles for retaining bodyfluids such as urine, menses, or faecal material, and in particular totheir ability to acquire and retain aqueous based materials. Theinvention further relates to disposable absorbent articles such as babydiapers or training pants, adult incontinence products, and femininehygiene products.

2. BACKGROUND

Disposable absorbent articles are well know from the art for receivingand retaining bodily discharges, such as urine, menstrual fluids, orfaecal materials. Thereby, two basic mechanisms are relied on. First,the containment of such discharges is generally achieved by a gasketingfunctionality, such as through impermeable materials or construction ofsealings between the article and—in most cases—the skin of the wearer.The other key mechanism is to retain the discharges within the absorbentarticle, generally achieved by using an absorbent structure to pick upthe discharges. In most cases, the absorption mechanism is directedtowards handling of the aqueous components of the discharges.

One of the key performance criteria against which an absorbent articlehas to deliver is the acquisition speed. Obviously, a fast liquidacquisition warrants a short time span between exudation and storage ofthe exudate. Another key performance criterion is the dryness of theuser facing surface of the absorbent article. To match the wearingcomfort of regular underwear, a dry touch of the user facing surface isdesired.

Thereby, one of the key transport and storage phenomena is related tothe capillary effects of the structures, whereby one property of thematerials used for constructing such structures is of criticalimportance is the porosity of the structure. The smaller the capillariesare the higher is the capillary suction.

Simultaneously, it has been a trend in recent absorbent articles toprovide the capability to handle high viscosity liquids such as faeces.Because of the high viscosity of such liquids, it is desirable that therespective acquisition structures provide large open pores in order toreadily accept such liquids. For example such structures are describedin WO 95/05139 (Roe), in PCT/US97/20840 (Bast et al.), and inPCT/US98/24389 (Roe et al.).

Inevitably, such large open pores limit the liquid handling capabilitiesof such open structures by reducing their capillary suction. Therefore,it has been suggested in the prior art to provide an absorbent articlewhich has good liquid acquisition performance in the front region andhas good high viscosity liquid handling capabilities in its back region.Such an absorbent article is described for example in PCT/US97/20841(Bast et al.).

Therefore, it is an object of the present invention to provide anabsorbent article which overcomes the problems posed by the prior artabsorbent articles.

It is a particular object of the present invention to provide anabsorbent article which has good low viscosity liquid handlingperformance as well as good high viscosity liquid handling performancein its front region.

It is a further object of the present invention provide an absorbentarticle which has a high in liquid acquisition speed and low liquidrewet through the topsheet.

It is a further object of the present invention provide an absorbentarticle which comprises a liquid handling structure having large openpores which effectively handles low viscosity liquids and high viscosityliquids such as faeces.

3. SUMMARY OF THE INVENTION

The present invention provides a disposable absorbent article having atransverse centerline, a first region, and a second region, the firstregion being positioned forward of the transverse centerline, the firstregion coming into contact with the front waist of the wearer duringuse, the second region being positioned backward of the transversecenterline, and the second region coming into contact with the backwaist of the wearer during use. The absorbent article of the presentinvention comprises a liquid pervious structured carrier, a liquidimpervious backsheet at least partially peripherally joined to thestructured carrier, a liquid storage structure positioned intermediatethe topsheet and the backsheet, and a liquid handling structurepositioned intermediate the topsheet and the liquid storage structure. Aportion of the liquid handling structure is positioned in the firstregion and a portion of the liquid handling structure is positioned inthe second region. The absorbent article of the present invention ischaracterised in that the absorbent article has a topsheet wetness valueof less than 120 milligrams according to theTopsheet-Finished-Product-Wetness Test Method disclosed herein and thedisposable absorbent article has a front region Storage Under Pressureunder pressure of at least 800 grams per square meter according to theStorage Under Pressure Test disclosed herein.

The present invention further provides a disposable absorbent articlewherein the disposable absorbent article has a front region totalproduct acquisition performance of more than 3.75 ml/s in the first gushand of more than 0.5 ml/s in the fourth gush.

The present invention further provides a disposable absorbent articlewherein the disposable absorbent article has a front region SkinHydration value of less 120 mg according to the Collagen Rewet TestMethod defined herein.

The present invention further provides a disposable absorbent articlewherein the disposable absorbent article has a front regionimmobilisation under compressed inversion of at least 70% according toImmobilisation Under Compressed Inversion Test disclosed herein.

The present invention further provides a disposable absorbent articlewherein the disposable absorbent article has a front region retentionunder compressed inversion of least 7.5 grams according to the RetentionUnder Compressed Inversion Test disclosed herein.

The present invention further provides a disposable absorbent articlewherein the disposable absorbent article has a back region Storage UnderPressure of at least 0.5 grams per square metre according to the StorageUnder Pressure Test disclosed herein.

The present invention further provides a disposable absorbent articlewherein the disposable absorbent article has a back regionimmobilisation under compressed inversion of at least 70% according tothe Immobilisation Under Compressed Inversion Test disclosed herein.

The present invention further provides a disposable absorbent articlewherein the disposable absorbent article has a back region retentionunder compressed inversion of at least 7.5 g according to the RetentionUnder Compressed Inversion Test disclosed herein.

The present invention further provides a disposable absorbent articlewherein the structured carrier comprises a plurality of apertures havinga size of at least 0.2 mm².

The present invention further provides a disposable absorbent whereinthe structured carrier has a open area of more than 12%.

The present invention further provides a disposable absorbent articlewherein the liquid handling structure has a compression resistance of atleast 70% under an applied pressure of 1 Newton per square centimeter.

The present invention further provides a disposable absorbent articlewherein the liquid handling structure has a resiliency of at least 50%after 30 seconds under an applied pressure of 1 Newton per squarecentimetre.

The present invention further provides a disposable absorbent articlewherein the liquid handling structure has a basis weight to uncompressedcalliper ratio of less than 100 grams per square meter per millimeter.

The present invention further provide a disposable absorbent articlewherein the liquid handling structure comprises a backing and a sheet offibres, the sheet of fibres having anchor portions in the backing atspaced bonding locations and having arcuate portions of the sheetprojecting from the backing between bonding locations.

4. BRIEF DESCRIPTION OF THE FIGURES

While the specification concludes with claims pointing out anddistinctly claiming the present invention, it is believed the same willbe better understood by the following drawings taken in conjunction withthe accompanying specification wherein like components are given thesame reference number and:

FIG. 1 is a plan view of an absorbent article embodiment of the presentinvention having portions cut away to reveal the underlying structure,the garment-facing surface of the diaper facing the viewer.

FIG. 2 is a perspective view of a liquid handling structure.

FIG. 3 is an illustration of the test setup for the Acquisition Test.

FIG. 4 is an illustration of the test set up for the Post AcquisitionCollagen Rewet Method.

FIG. 5 is a schematic front view of an apparatus which may be used tomeasure Acceptance Under Pressure and Storage Under Pressurecharacteristics of structures.

FIG. 6 is a schematic.side view of an apparatus which may be used tomeasure retention and Immobilization Under Compressed Inversioncharacteristics of structures.

FIG. 7 is a plan view of a piece of a standard storage element.

FIG. 8 is a schematic front view of an apparatus which may be used tomeasure trans-topsheet capacity characteristics of structures.

5. DETAILED DESCRIPTION OF THE INVENTION

The absorbent article of the present invention is described in thefollowing by means of a variety of different embodiments and by means ofa variety of different features. Further embodiments of the presentinvention may be obtained by combining features of one embodiment withfeatures of another embodiment disclosed herein and/or with otherfeatures disclosed herein. These further embodiments are considered tobe implicitly disclosed herein and hence form part of the presentinvention. It will be apparent to the skilled person that combinationsof certain features may lead to non-functional articles not forming partof the present invention.

5.1 Absorbent Article

As used herein, the term “absorbent article” refers to devices whichabsorb and contain body exudates, and, more specifically, refers todevices which are placed against or in proximity to the body of thewearer to absorb and contain the various exudates discharged from thebody. The term “disposable” is used herein to describe absorbentarticles which are not intended to be laundered or otherwise restored orreused as an absorbent article (i.e., they are intended to be discardedafter a single use and, preferably, to be recycled, composted orotherwise disposed of in an environmentally compatible manner). A“unitary” absorbent article refers to absorbent articles which areformed of separate parts united together to form a coordinated entity sothat they do not require separate manipulative parts like a separateholder and liner. A preferred embodiment of an absorbent article of thepresent invention is the unitary disposable absorbent article, diaper20, shown in FIG. 1. As used herein, the term “diaper” refers to anabsorbent article generally worn by infants and adult incontinentpersons and is worn about the lower torso of the wearer. The presentinvention is also applicable to other absorbent articles such asincontinence briefs, incontinence undergarments, absorbent inserts,diapers holders and liners, feminine hygiene garments, and the like.

5.2 Diaper

FIG. 1 is a plan view of the diaper 20 of the present invention in aflatout, state with portions of the structure being cut-away to moreclearly show the construction of the diaper 20. The portion of thediaper 20 which faces the wearer is oriented towards the viewer. Asshown in FIG. 1, the diaper 20 preferably comprises a liquid perviousstructured carrier 24; a liquid impervious backsheet 26; an liquidstorage structure 28, which is preferably positioned between at least aportion of the structured carrier 24 and the backsheet 26; a liquidhandling structure 29 positioned between the structured carrier 24 andthe liquid storage structure 28; side panels 30; elasticised leg cuffs32; an elastic waist feature 34; and a fastening system generallydesignated 40.

Diaper 20 is shown in FIG. 1 to have a front waist region 36, a rearwaist region 38 opposed to the front waist region 36 and a crotch region37 located between the front waist region and the rear waist region. Thediaper 20 further has a first region 81 juxtaposed with the front of thewearer while the diaper 20 is being worn and a second region 82 opposedto the first region 81 and juxtaposed with the back of the wearer whilethe diaper 20 is being worn. The periphery of the diaper 20 is definedby the outer edges of the diaper 20 in which the longitudinal edges 50run generally parallel to the longitudinal centerline 100 of the diaper20 and the end edges 52 run between the longitudinal edges 50 generallyparallel to the lateral centerline 110 of the diaper 20. In FIG. 1 thefirst region 81 is shown as extending from one end edge 52 to thelateral centerline 110 and the second region 82 is shown as extendingfrom the opposing end edge 52 to the lateral centerline 110. Forpurposes of discussion, the lateral centerline 110 is shown as theboundary between the first region 81 and the second region 82 in FIG. 1.However, the boundary between the first region 81 and the second region82 may be positioned at other locations, for example closer to one ofthe respective end edges 52. The first region 81 being juxtaposed withthe front of the wearer should be superior in the handling of urine. Thesecond region being juxtaposed with the back of the wearer should besuperior in the handling of faecal material, in particular low-viscosityfaecal material.

The chassis 22 of the diaper 20 comprises the main body of the diaper20. The chassis 22 comprises at least a portion of the liquid storagestructure 28 and preferably an outer covering layer including thestructured carrier 24 and the backsheet 26. If the absorbent articlecomprises a separate holder and a liner, the chassis 22 generallycomprises the holder and the liner. (For example, the holder maycomprise one or more layers of material to form the outer cover of thearticle and the liner may comprise an absorbent assembly including astructured carrier, a backsheet, and an liquid storage structure. Insuch cases, the holder and/or the liner may include a fastening elementwhich is used to hold the liner in place throughout the time of use.)For unitary absorbent articles, the chassis 22 comprises the mainstructure of the diaper with other features added to form the compositediaper structure.

FIG. 1 shows an embodiment of the diaper 20 in which the structuredcarrier 24 and the backsheet 26 have length and width dimensionsgenerally larger than those of the liquid storage structure 28 and theliquid handling structure 29. The structured carrier 24 and thebacksheet 26 extend beyond the edges of the liquid storage structure 28to thereby form the periphery of the diaper 20.

While the structured carrier 24, the backsheet 26, and the chassis 22may be assembled in a variety of well known configurations, preferreddiaper configurations are described generally in U.S. Pat. No. 3,860,003entitled “Contractible Side Portions for Disposable Diaper” which issuedto Kenneth B. Buell on Jan. 14, 1975; and U.S. Pat. No. 5,151,092 issuedto Buell on Sep. 9, 1992; and U.S. Pat. No. 5,221,274 issued to Buell onJun. 22, 1993. Other suitable diaper chassis design are disclosed inU.S. Pat. No. 5,569,232 entitled “Absorbent Article With Multiple ZoneStructural Elastic-Like Film Web Extensible Waist Feature” which issuedto Roe et al. on Oct. 29, 1996; U.S. Pat. No. 5,554,144 entitled“Absorbent Article With Multiple Zone Structural Elastic-Like Film WebExtensible Waist Feature” which issued to Roe et al. on Sep. 10, 1996;U.S. Pat. No. 5,554,143 entitled “Absorbent Article With Multiple ZoneStructural Elastic-Like Film Web Extensible Waist Feature” which issuedto Roe et al. on Sep. 10, 1996; U.S. Pat. No. 5,554,145 entitled“Absorbent Article With Multiple Zone Structural Elastic-Like Film WebExtensible Waist Feature” which issued to Roe et al. on Sep. 10, 1996;U.S. Pat. No. 5,556,394 entitled “Absorbent Article With. Multiple ZoneStructural Elastic-Like Film Web Extensible Waist Feature” which issuedto Roe et al. on Sep. 17, 1996. Each of these references is herebyincorporated by reference herein.

The inner surface of the diaper 20 comprises that portion of the diaper20 which is adjacent to the wearer's body during use (i.e., the innersurface generally is formed by at least a portion of the structuredcarrier 24 and other components joined to the structured carrier 24).The outer surface comprises that portion of the diaper 20 which ispositioned away from the wearer's body (i.e., the outer surfacegenerally is formed by at least a portion of the backsheet 26 and othercomponents joined to the backsheet 26) during use.

5.3 Aqueous Liquid Handling Performance

The liquid handling performance for aqueous liquids is a key feature ofthe present invention. The term “aqueous liquids” as used hereinincludes but is not limited to body exudates such as urine, faecalmaterial, menses, blood, sweat.

5.3.1 Liquid Flow Path

To further explain the present invention, the following describes thefluid flow path through the absorbent article, from the “loading point”where the fluid first hits the article to the “ultimate storage region”,i.e. that region of the article where the fluid is intended to be storedwith minimal impact on the wearer. Modern diaper designs often use socalled superabsorbent materials, but other structures comprising fluidbinding means are also covered by the scope of the present invention.

When the fluid is first contacting the article, the so-called“acquisition phase”, it is desirable to have the fluid penetrating intothe pores/openings of the article as quickly as possible. This isenhanced by larger openings, and/or a hydrophilic surface of thematerial.

The next phase of the fluid handling in absorbent structures, theso-called storage phase”, relates to transporting fluid to more or lessremote locations for ultimate storage.

5.3.2 Liquid Flow Mechanisms

Generally spoken, liquid transport can be achieved by two mechanisms:

(1)—“free flow” whereby gravity is the driving force. This type of flowis enhanced by large open pores, and low surface energies, i.e.hydrophilic surfaces. However, this flow is per definition only in thedirection of the gravity—which sometimes might be useful, but more oftenit is a strong constraint for accommodating for example different usesituations such as position of the wearer etc.

(2)—“capillary flow” whereby capillary forces dominate. This flowmechanism allows to overcome the gravity dominated flow. One of theequations used to describe the capillary flow is the Laplace equation$P_{c} = \frac{2\quad \gamma \quad \cos \quad \theta}{R}$

where P_(c) is the capillary pressure, γ is the surface tension of theliquid, θ is the contact angle between the liquid and the surface of thecapillary, and R is the radius of the capillary.

It can readily be seen from this equation, that in order to increase thecapillary pressure which is the driving force behind capillary flow, oneneeds to

lower the contact angle by maximising the difference between the surface

energy of the capillary and the surface tension of the liquid

provide small capillaries

increase the surface tension of the liquid to be transported, or—inother words—eliminate instances where the surface tension of the liquidis reduced

However, there also exist constraints when designing an absorbentarticle which will be explained in more detail in the respectivecontext.

5.3.3 Hydrophilicity

The disposable absorbent article of the present invention comprisesmaterials of different hydrophilicities in order to optimise the fluidhandling of the article.

One way to express hydrophilicity is via the contact angle measurement,whereby the angle is meant which is formed when a drop of liquid in onthe surface of a solid material in an gas (generally air) environment.The more hydrophobic a material is, the larger the contact angle will beand—in the extreme—the fluid will form an almost spherical drop sittingon the surface. The more hydrophilic a material is, the more the fluidwill spread, and—in the extreme—almost cover the surface as a thin film.

Often, materials having a contact angle of less than are calledhydrophilic, of more than hydrophobic. For the exact scope of thepresent invention, however, the exact determination of the contact angleis not essential, but rather whether a certain material is treated suchthat it is more hydrophilic than the untreated material, such that whenthe difference in a certain measurement technique is larger than theaccuracy of this method.

There exist a number of suitable materials for making fluid handlingelements, which readily satisfy this requirement of being wettable, orsufficiently hydrophilic. In particular, naturally occurring materials,such as cellulose based fibrous materials, or cellulosic sponges, have anatural hydrophilicity, i.e. they have, due to their chemicalcomposition (OH) -groups or other active sites on the surface resultingin specific surface energies as to allow to be readily wetted by aqueousfluids.

There exists, however, another group of materials which are relativelyhydrophobic in their nature, such as by having due to their chemicalcomposition only very few (OH) -groups or other polar sites on theirsurface. The most well known exemplifying materials are made of olefinpolymers, such as polyethylene or polypropylene, but many other,including also bi-component structures comprising such materials can becontemplated. Conventional glues—and especially of the “hot-melttype”—generally comprise a number of different components, such asstructural polymers, tackifiers, resins etc., most of these also beinghydrophobic in nature.

In spite of their hydrophobicity such materials can still be attractivefor being used in disposable absorbent articles for other reasons suchas their broad availability, easy processing, the good disposabilityafter use.

Thus, it is common state of the art, to overcome the hydrophobicity bytreating such man-made hydrophobic polymers with hydrophilizing agents,or “surfactants”, or surface active agents. These agents can be appliedto the surface of the fibres, or webs, or film materials. As, forexample, described in EP-A-0.340.763 (Hansen), the surfactants also canbe incorporated into the resin at relatively low percentages, such thatthe (essentially hydrophobic) base resin (e.g. polypropylene) comprisesfrom about 0.5% to 3% (on total weight basis). hydrophilizing agent.These hydrophilizing agents can be homogeneously distributed throughoutthe resin, or they can be distributed such that they have a higherconcentration towards the surface, and even might not be present indetectable amounts in a region more remote from the surface, e.g. in thecore of a fibre. Effective for the wettability is only the portion ofthe hydrophilizing agent on the surface of the material.

The liquid handling of the absorbent article of the present inventionmay be supported by comprising materials which exhibit increasinghydrophilicity along the flow path. Such a hydrophilicity gradientpromotes liquid transport from one material onto the next by increasingthe capillary pressure via contact angle decrements.

The first material in the liquid flow path, i.e. the material whichcomprises the loading point, is the structured carrier 24 of theabsorbent article. This material is also the material which comes intocontact with the skin of the wearer during use of the article. Becauseof the latter, it is desirable that the structured carrier is as dry aspossible during use. Dryness of the structured carrier is basicallygoverned by two factors, the liquid retention within the structuredcarrier and liquid coming back along the liquid flow path in the reversedirection. Deployment of a hydrophobic structured carrier improves itsdryness with regard to both of these factors. If the capillary suctionof the structured carrier is reduced by being hydrophobic, less liquidcan be retained ion the pores of the structured carrier and liquid rewetfrom the lower layers is suppressed.

From a liquid acquisition point of view the hydrophobicity of thestructured carrier is obviously detrimental. However, it has been foundthat when the structured carrier of the present invention is providedwith apertures, i.e. macroscopic pores, it is possible to combine thefeature of surface hydrophobicity with the overall liquid acquisitionrequirements of absorbent articles.

The liquid handling structure of the present invention which is placedimmediately beneath the structured carrier needs to be at leastpartially hydrophilic to assist liquid acquisition through the aperturesof the structured carrier. To promote liquid acquisition also forsubsequent gushes, it is desired that the liquid handling structure ofthe present invention does not become substantially more hydrophobicduring use.

The liquid storage structure of the present invention also needs to behydrophilic and preferably more hydrophilic than the liquid handlingstructure in order to transfer liquid from the liquid handling structureinto the liquid storage structure and in order to retain liquid withinthe liquid storage structure.

5.3.4 Pore Sizes

In order to transport the liquid along the liquid flow path it isdesirable to provide different material with decreasing pore sizes alongthe flow path. Materials with a smaller pore size exhibit a highercapillary pressure than a material with a larger pore size. Thus,materials with smaller pores are able to actively acquire liquids frommaterial with larger pores, in other words they are able to dewater theother material.

Hence, the absorbent article of the present invention preferablycomprises different materials along the liquid flow path which exhibit adecreasing pore size in order to promote liquid transport along the flowpath.

As already mentioned, the structured carrier of the present invention isrequired to have apertures to allow liquid penetration despite thehydrophobicity of the structured carrier. The liquid handling structureof the present invention preferably has large pores in order to allowquick acquisition of body exudates including medium and high viscosityliquids such as menses and faecal material. The liquid storage structurepreferably has small pores in order to provide capillary suction totransfer and to store at least the aqueous components of the bodyexudates in the liquid storage structure.

5.3.5 Surface Tension of the Liquid

The effects of surface tension and surface energies of fluids and wettedmaterials on fluid transport properties have been widely discussed, suchas in Chatterjee “Absorbency” (Elsevier, Amsterdam, 1985).

However, inventors have realised, that it is not only important to lookat the wetting of the materials by the fluids, including the aim ofmaintaining the properties over subsequent wetting cycles, but also tolook at the change of the properties of the discharged fluid and toexploit this finding to optimise the choice of materials for and theirimproved arrangement in absorbent structures.

From the Laplace equation above, it can be seen that a reduction of thesurface tension of the liquid to be acquired is detrimental to thecapillary pressure and the liquid handling of the different materials.

Hence, it is an optional feature of the present invention that theabsorbent article maintains a high surface tension of the liquids, asthey pass through the various hydrophilised materials of the absorbentarticle. In other words, it is optional element of the present inventionthat those elements of the absorbent article which are treated withsurfactants to become more hydrophilic, not or only to a small extentloose these surfactants to the fluid.

Conventional agents such as commonly used Nonylphenol ethoxylates (NPE)can be readily removed, whilst materials according to the teachings ofthe present invention essentially do not reduce the surface tension ofliquids passing through. This applies to all functional elements alongthe liquid flow path, structured carrier, liquid handling structure, andliquid storage structure.

Within the scope of the conventional surfactant technology, significanteffort has already been spent against maintaining the hydrophilicity ofthe surface even after being in contact with an aqueous fluids, whichattempt to wash away the surfactants. This can be achieved by getting astronger bond between the (hydrophobic) polymer and the surfactant (suchas described for example in EP-A-0.598.204 (Garavaglia) or WO 95/10648(Everhardt)), or by replacing the surfactant which is washed away fromthe surface by diffusing mechanisms from the core of the polymer.

Furthermore, it is an optional element of the present invention to addmaterials to the absorbent structure to increase the surface tension ofthe penetrating fluid, so-called “scavenging agents”, such as tomaximise the wicking capability afterwards. The technologies forincreasing surface tensions of fluids are available in differenttechnology fields such as in the detergent area and the like.Essentially, there are two paths to achieve this. The first is by addingelectrolytes to the solution. When doing so in the context of thepresent invention, care needs to be taken to not add contaminants forfurther fluid handling steps. For example, it is well known, that inparticular two valent metal ions such as Ca⁺⁺can have a detrimentaleffect on certain absorbency properties of the superabsorber. The secondpath to increase surface tension is to add high surface area agents suchas activated carbon, zeolithes, and the like to the absorbent article.Such agents adsorb the surfactant at their surface thereby restrictingthe mobility of the surfactant. Such immobilises surfactant may not anylonger migrate to the surface of the liquid thereby reducing the surfacetension of the liquid.

5.3.6 Liquid Acquisition

The term “liquid acquisition” as used herein refers to the rate at whichliquid which is deposited on top of the structured carrier of thepresent invention is absorbed from the surface of the structured carrierinto the absorbent article.

The liquid acquisition performance of the absorbent article of thepresent invention is assessed via the Finished-Product-Acquisition Testas described hereinafter.

The absorbent article of the present invention has a liquid acquisitionrate of at least 3.75 ml/s in the first gush, preferably of at least 4ml/s in the first gush, more preferably at least 4.5 ml/s in the firstgush, and most preferably at least 5 ml/s in the first gush. Theabsorbent article of the present invention further has a liquidacquisition rate of at least 0.5 ml/s in the fourth gush, preferably atleast 0.6 ml/s in the fourth gush, more preferably at least 0.8 ml/s inthe fourth gush, and most preferably at least 1.0 ml/s in the fourthgush.

5.3.7 Liquid Rewet

The term “liquid rewet” as used herein refers to already acquired liquidthat is subsequently squeezed out through the structured carrier of aloaded absorbent article under pressure.

The liquid rewet performance of the absorbent article of the presentinvention is assessed via the Collagen Rewet Test as describedhereinafter and is quantified by the Skin Hydration value.

The front region of the absorbent article of the present invention has aSkin Hydration value of less than 120 mg, preferably a Skin Hydrationvalue of less than 90 mg, more preferably a Skin Hydration value of lessthan 70 mg, and most preferably a Skin Hydration value of less than 50mg.

Optionally, the back region may have a Skin Hydration value of less than120 mg, preferably a Skin Hydration value of less than 90 mg, morepreferably a Skin Hydration value of less than 70 mg, and mostpreferably a Skin Hydration value of less than 50 mg.

5.3.8 Topsheet Wetness

In order to support the dry touch of the user facing surface of theabsorbent article of the present invention, the absorbent article of thepresent invention preferably has a topsheet wetness of less than 300 mg,more preferably less than 200 mg, even more preferably less than 100 mg,even more preferably less than 80 mg, most preferably less than 50 mgaccording to the Topsheet-Finished-Product-Dryness disclosedhereinafter.

5.4 High Viscosity Liquid Handling

In addition, the absorbent article of the present invention preferablyprovides high viscosity liquid handling, and in particular liquidhandling of viscous fluid body waste.

As used herein, the term “viscous fluid bodily waste” or “VFBW”generally refers to any waste discarded from the body which has aviscosity of greater than about 10 cP and less than about 2×10⁵ cP at ashear rate of one 1/sec, (at about 35 degrees C), more particularlybetween about 10³ cP and 10⁵ cP at a one 1/sec shear rate, in acontrolled stress rheometry test using parallel plates on a controlledstress rheometer. (For reference, water is at 1.0 cP at 20 degrees C andJif Creamy peanut butter (available from the Procter & Gamble Co.,Cincinnati., Ohio.) is approximately 4×10⁵ cP at 25 degrees C at thissame shear rate). The method for determining viscosity, as used herein,is described in detail in the Test Method section below.

5.4.1 Storage Under Pressure

Once viscous fluid bodily waste has penetrated the liquid handlingstructure, it is desirable to store or hold the waste away from thewearer during the remainder of the wearing cycle and away from thecaregiver during the changing process. As used herein, the term “store”refers to the physical separation of material deposited in a diaper fromthe body-facing surface of the article such that the material depositedin the diaper is not immediately in contact with or accessible to thewearers skin. Storage Under Pressure, or “storage,” is measured as theamount of material held in the structure on a unit area basis, asdescribed in the Test Method Section below. If the Storage UnderPressure capacity is too low, the absolute quantity of viscous fluidbodily waste that can be stored away from skin access per unit area ofthe structure will be reduced. Adequate storage capacity is essential toreduce the probability of leakage and the area of skin contaminated byviscous fluid bodily waste because viscous fluid bodily waste that hasbeen stored is less likely to be available to the body-facing surface ofthe structure for leakage and migration within the article.

In preferred embodiments of the present invention the absorbent articleshould include a liquid handling structure having a Storage UnderPressure value greater than about 800 grams per square meter (g/m²) ofthe liquid handling structure of viscous fluid bodily waste. Morepreferably, the liquid handling structure should have a Storage UnderPressure value greater than about 900 g/m² of viscous fluid bodilywaste. Even more preferably, the liquid handling structure should have aStorage Under Pressure value greater than about 1000 g/m² of viscousfluid bodily waste, and most preferably greater than about 1100 g/m² ofviscous fluid bodily waste. Generally, Storage Under Pressure valuesbetween at least about 800 g/m² and about 10000 g/m², and between about1000 g/m² and about 10000 g/m² have been found to be acceptable. (Thesepreferred Storage Under Pressure parameters relate to integratedarticles which are preferably evaluated as they are intended for use.Accordingly, all of the components or layers of the article should beconfigured as they would be during normal use when the measurement oftheir performance is made. A more detailed description of the method fordetermining Storage Under Pressure performance is included in the TestMethods section, below.)

5.4.2 Retention and Immobilization Under Compressed Inversion

Viscous fluid bodily waste that is accepted by, or penetrates, theabsorbent article is preferably also retained in the diaper away fromthe wearer. One preferred way to retain bodily waste, especially viscousfluid bodily waste, is to immobilise the waste in a location away fromthe wearer. As used herein, the term “immobilise” refers to the abilityof the material or structure to retain stored viscous fluid bodily wasteunder an applied pressure and/or the influence of gravitational forces.Immobilisation Under Compressed Inversion, or “immobilisation,” may beaccomplished by increasing the waste's viscosity (e.g., by dewatering),by mechanical entrapment (i.e., a surface energy phenomenon driven byincreased surface area of contact of the viscous fluid bodily wasteswith the internal regions of the material or structure) or by any othermeans known in the art. “Immobilisation Under Compressed Inversion,” asdescribed further in the Test Method Section below, is measured in termsof the percentage of the viscous fluid bodily waste or analogue thatremains in the structure after the structure is subjected to an invertedpressure cycle, as described below. “Retention Under CompressedInversion”, or “retention,” is an absolute measure of how much viscousfluid bodily waste remains “stored” under stressful usage conditions.

Preferably, the liquid handling structure should have a Retention UnderCompressed Inversion value of greater than about 7.5 g of the viscousfluid bodily waste which penetrates the structure. More preferably, theliquid handling structure should have a Retention Under CompressedInversion value of greater than about 8.0 g of viscous fluid bodilywaste, and most preferably greater than about 8.5 g of viscous fluidbodily waste after being subjected to the Retention Under CompressedInversion test, as described below. Generally, Retention UnderCompressed Inversion values between at least about 7.5 g and about 100.0g, and between about 8.0 g and about 100.0 g have been found to beacceptable. Under the same conditions, the liquid handling structureshould have an Immobilisation Under Compressed Inversion value of atleast 70% of the viscous fluid bodily waste accepted by the liquidhandling structure. More preferably, the liquid handling structureshould have an Immobilisation Under Compressed Inversion value of atleast about 80% and most preferably at least about 85% of the viscousfluid bodily waste accepted by the element 120. Generally,Immobilisation Under Compressed Inversion values between at least about70% and about 100%, and between about 80% and about 100% have been foundto be acceptable. (These preferred Immobilisation and Retention UnderCompressed Inversion parameters relate to integrated articles which arepreferably evaluated as they are intended for use. Accordingly, all ofthe components or layers of the article should be configured as theywould be during normal use when the measurement of their performance ismade. A more detailed description of the method for determiningImmobilisation and Retention Under Compressed Inversion performance isincluded in the Test Methods section, below.)

Without the appropriate immobilisation and retention performance, theeffects of improved acceptance and storage performance may be diminishedbecause the viscous fluid bodily waste may return to the body-facingsurface of the structure, increasing the likelihood of leakage orcontamination of the wearer's skin. Further, immobilisation is mosteffective if the structure first accepts the waste and then stores it.Viscous fluid bodily waste that is immobilised prior to being storedaway from the wearer's skin may remain on the structured carrier incontact with the skin. Immobilising viscous fluid bodily waste which isin contact with the skin can increase the effort required by thecaregiver during the changing/cleaning process and increases thelikelihood of residual, micro-level contamination. “Micro-levelcontamination” refers to waste residue which remains on the skin, but isnot easily visible to the human naked eye. Therefore, it may be helpfulto consider at least three parameters (acceptance, storage, andimmobilisation or acceptance, storage and retention) for a givenstructure when determining its utility for effectively managing viscousfluid bodily wastes.

In some embodiments, it may be desirable to provide the diaper 20 withdifferent acceptance performance in different portions of the diaper.This may be accomplished by providing a single structured carrier whichhas been manufactured or treated to have regions of differing acceptancecharacteristics. Further, the structured carrier may be elevated abovethe plane of the body-facing surface of the article so as to be inbetter control of exuded viscous fluid bodily wastes. In someembodiments, it may even be desirable to have the structured carrier incontact with skin of wearer in proximity of the viscous fluid bodilywaste source (e.g., the perianal region).

The trans-topsheet capacity as measured by the trans-topsheet capacitytest as disclosed hereinafter reflects the diapers ability to handlelow-viscosity faecal material. First region 81 and second region 82 ofthe diaper 20 should have a relatively high trans-topsheet capacity.

There is an inverse relationship between the minimum trans-topsheetcapacity necessary to handle low-viscosity faecal material and thesurface area of the diaper 20 having this minimum capacity. As a largerpercentage of the diaper 20 surface area has a trans-topsheet capacitysufficient to handle low-viscosity faecal material, the necessarytrans-topsheet capacity diminishes.

In any case, the first region 81 and the second region 82 of the diaper20 preferably have a trans-topsheet capacity of at least about 300 gramsper square inch provided that an surface area at least 0.02 squaremeter.of the diaper 20 has such a trans-topsheet capacity and preferablyat least 0.03 square meter of the diaper 20 has such a trans-topsheetcapacity.

At least a portion of the first region 81 and at least a portion thesecond region 82 of diaper 20 according to the present inventionpreferably provides a trans-topsheet capacity of at least 300 grams persquare meter, more preferably at least 400 grams per square meter, evenmore preferably at least 500 grams per square meter, still morepreferably at least 600 grams per square meter, and most preferably atleast 700 grams per square meter.

5.5 Liquid Storage Structure

5.5.1 Liquid Storage

The liquid storage structure 28 may be any absorbent means which isgenerally compressible, conformable, non-irritating to the wearers skin,and capable of absorbing and retaining liquids such as urine and othercertain body exudates. As shown in FIG. 1, the liquid storage structure28 has a garment surface, a body surface, side edges, and waist edges.The liquid storage structure 28 may be manufactured in a wide variety ofsizes and shapes (e.g., rectangular, hourglass, “T”-shaped, asymmetric,etc.) and from a wide variety of liquid-absorbent materials commonlyused in disposable diapers and other absorbent articles such ascomminuted wood pulp which is generally referred to as airfelt. Examplesof other suitable absorbent materials include creped cellulose wadding;meltblown polymers including coform; chemically stiffened, modified orcross-linked cellulosic fibres; tissue including tissue wraps and tissuelaminates; absorbent foams; absorbent sponges; superabsorbent polymers;absorbent gelling materials; or any equivalent material or combinationsof materials.

The configuration and construction of the liquid storage structure 28may also be varied (e.g., the liquid storage structure 28 may havevarying calliper zones, a hydrophilicity gradient, a pore size gradient,a superabsorbent gradient, or lower average density and lower averagebasis weight acquisition zones; or may comprise one or more layers orstructures). The total absorbent capacity of the liquid storagestructure 28 should, however, be compatible with the design loading andthe intended use of the diaper 20. Further, the size and absorbentcapacity of the liquid storage structure 28 may be varied to accommodatewearers ranging from infants through adults.

Exemplary absorbent structures for use as the liquid storage structure28 are described in U.S. Pat. No. 4,610,678 entitled “High-DensityAbsorbent Structures” issued to Weisman et al. on Sep. 9, 1986; U.S.Pat. 4,673,402 entitled “Absorbent Articles With Dual-Layered Cores”issued to Weisman et al. on Jun. 16, 1987; U.S. Pat. 4,888,231 entitled“Absorbent Core Having A Dusting Layer” issued to Angstadt on Dec. 19,1989; and U.S. Pat. No. 4,834,735, entitled “High Density AbsorbentMembers Having Lower Density and Lower Basis Weight Acquisition Zones”,issued to Alemany et al. on May 30,1989.

5.5.2 Wrap Sheets

The liquid storage structure of the present invention may furthercomprise at least one wrap sheet. The wrap sheet covers the absorbentstructure at least at a part of the surface of the absorbent structure,such that the fluid path from the liquid receiving area to the liquidstorage structure will pass through the web. Thus the meaning of theterm “wrapping” should not be read to mean complete wrapping orenveloping only. An example for such an embodiment can be a wrap-sheetcovering the top surface of the liquid storage structure, and then beingtacked down next to the core, such that the side surface can be but notnecessarily have to be covered by the wrap sheet.

In a preferred embodiment, the wrap-sheet covers also other surfaces ofthe liquid storage structure, in one preferred embodiment, it covers allsix surfaces, such that the liquid storage structure is completelyenveloped. Another preferred and more easy to manufacture embodimentcovers the top surface as well as two side surfaces by being foldedaround these to partly of fully cover the bottom surface.

The wrapping of the absorbent member can also be achieved by more thanmore than one wrap-sheet, or by one wrap sheet with different propertiesin different regions thereof. For example, the surface parts of theabsorbent member which are not in the fluid flow path, can have no, ornon-permanent fluid hydrophilicity. Or, a different wrap material can beused in such regions, or the absorbent member materials can there becontained by other elements, such as conventional tissue materials, butalso impermeable sheets, which may at the same time has otherfunctionality, such as a backsheet material.

Of course, it is an essential requirement, that the absorbent structureand the wrap sheet are in fluid communication with each other, such thatthe fluid flow path, and particularly the capillary transport gradientwill not be interrupted. A preferred embodiment of this is a design,where the wrap sheet and the absorbent structure are in direct contactwith each other—at least for the surfaces as described in the above.

It is generally known in the art, to manufacture suitable wrap sheetsfrom tissue layers, nonwbvens, and the like. Preferred nonwovenmaterials to be used for the wrap sheets of the present invention aredisclosed for example in European patent application 98107288.7 (Fuchs).These hydrophilic materials exhibit a low surfactant release to theacquired liquid and hence do not negatively impact the liquid handlingof the absorbent article of the present invention in order to notnegatively impact the liquid handling of the absorbent article of thepresent invention, a suitable wrap sheet has a surface tension reductionvalue of less than 15 mN/m, preferably less than 12 mN/m, morepreferably less than 9 mN/, even more preferably less than 6 mN/m, andmost preferably of less than 3 mN/m according to the surface tensionreduction test defined hereinafter.

5.6 Backsheet

The backsheet 26 is positioned adjacent the garment surface of theliquid storage structure 28 and is preferably joined thereto byattachment means (not shown) such as those well known in the art. Asused herein, the term “joined” encompasses configurations whereby anelement is directly secured to the other element by affixing the elementdirectly to the other element, and configurations whereby the element isindirectly secured to the other element by affixing the element tointermediate member(s) which in turn are affixed to the other element.

For example, the backsheet 26 may be secured to the liquid storagestructure 28 by a uniform continuous layer of adhesive, a patternedlayer of adhesive, or an array of separate lines, spirals, or spots ofadhesive. Adhesives which have been found to be satisfactory aremanufactured by H. B. Fuller Company of St. Paul, Minn. and marketed asHL-1258. The attachment means will preferably comprise an open patternnetwork of filaments of adhesive as is disclosed in U.S. Pat. No.4,573,986 entitled “Disposable Waste-Containment Garment”, which issuedto Minetola et al. on Mar. 4, 1986, more preferably several lines ofadhesive filaments swirled into a spiral pattern such as is illustratedby the apparatus and methods shown in U.S. Pat. No. 3,911,173 issued toSprague, Jr. on Oct. 7, 1975; U.S. Pat. No. 4,785,996 issued to Ziecker,et al. on Nov. 22, 1978; and U.S. Pat. No. 4,842,666 issued to Wereniczon Jun. 27, 1989. Each of these patents is incorporated herein byreference. Alternatively, the attachment means may comprise heat bonds,pressure bonds, ultrasonic bonds, dynamic mechanical bonds, or any othersuitable attachment means or combinations of these attachment means asare known in the art.

The backsheet 26 is impervious to liquids (e.g., urine) and ispreferably manufactured from a thin plastic film, although otherflexible liquid impervious materials may also be used. As used herein,the term “flexible” refers to materials which are compliant and willreadily conform to the general shape and contours of the human body.

The backsheet 26 prevents the exudates absorbed and contained in theliquid storage structure 28 from wetting articles which contact thediaper 20 such as bedsheets and undergarments. The backsheet 26 may thuscomprise a woven or nonwoven material, polymeric films such asthermoplastic films of polyethylene or polypropylene, or compositematerials such as a film-coated nonwoven material. Preferably, thebacksheet 26 is a thermoplastic film having a thickness of about 0.012mm (0.5 mil) to about 0.051 mm (2.0 mils). Particularly preferredmaterials for the backsheet 26 include RR8220 blown films and RR5475cast films as manufactured by Tredegar Industries, Inc. of Terre Haute,Ind. The backsheet 26 is preferably embossed and/or matte finished toprovide a more cloth-like appearance. Further, the backsheet 26 maypermit vapours to escape from the liquid storage structure 28 (i.e., bebreathable) while still preventing exudates from passing through thebacksheet 26.

5.7 Structured Carrier

The structured carrier 24 of the present invention has a first or innersurface oriented toward the interior of the disposable diaper,specifically oriented toward the liquid storage structure 28, and anopposed second or outer surface oriented toward the skin of the wearerwhen the diaper is worn.

The structured carrier 24 is juxtaposed with, but not necessarilyadjacent the body surface of the liquid storage structure 28, and ispreferably joined to the backsheet 26 or liquid storage structure 28 bymeans such as those well known in the art. In a preferred embodiment ofthe present invention, the structured carrier 24 and the backsheet 26are joined directly to each other in the diaper periphery.

The structured carrier 24 is compliant, soft feeling, and non-irritatingto the wearer's skin. Further, the structured carrier 24 is liquidpervious, permitting liquids (e.g., urine) to readily penetrate throughits thickness. A suitable structured carrier 24 may be manufactured froma wide range of materials, such as porous foams; reticulated foams;apertured plastic films; or woven or nonwoven webs of natural fibres(e.g., wood or cotton fibres), synthetic fibres (e.g., polyester orpolypropylene fibres), or a combination of natural and synthetic fibres.Preferably, the structured carrier 24 is made of a hydrophobic materialto isolate the wearer's skin from liquids contained in the liquidstorage structure 28.

5.7.1 General Properties

5.7.1.1 Functional Properties

The structured carrier of the present invention is hydrophobic and inorder to minimise liquid retention in the structured carrier and tominimise liquid rewet from the liquid handling structure or the liquidstorage structure back to the skin of the wearer.

Optionally, the structured carrier of the present invention may also beoleophobic in order to minimise liquid retention in the structuredcarrier and to minimise liquid rewet from the liquid handling structureor the liquid storage structure back to the skin of the wearer.

The structured carrier of the present invention has a liquid retentionin the topsheet according to the Liquid-Retention Test definedhereinafter of less than 50 mg , preferably less than 40 mg, morepreferably less than 30 mg, most preferably less than 20 mg for a testliquid having a surface tension of about 62 mN/m.

The structured carrier of the present invention has a liquid retentionin the topsheet according to the Liquid-Retention Test definedhereinafter of less than 150 mg , preferably less than 120 mg, morepreferably less than 90 mg, most preferably less than 70 mg for a testliquid having a surface tension of about 33 mN/m.

The contact angle of the user facing side of the structured carrier ofthe present invention with distilled water having a surface tension ofat least 72 mN/m is at least 90°, preferably at least 100°, morepreferably at least 110°, even more preferably at least 120°, mostpreferably more than 125°. High contact angles reduce the capillarysuction of the pores of the structured carrier. Contact angles of morethan 90° even result in a negative the capillary suction, hencerendering the respective pores water repellent.

5.7.1.2 Structural Properties

The structured carrier 24 preferably has a plurality of apertures withan effective aperture size of at least 0.2 square millimetres, morepreferably, the plurality of apertures have an effective aperture sizeof at least 0.5 square millimetres, even more preferably, the pluralityof apertures have an effective aperture size of at least 1.0 squaremillimetres, and most preferably, the plurality of apertures have aneffective aperture size of at least 2.0 square millimetres. Effectiveapertures are those which have a grey level of 18 or less on a standardgrey level scale of 0-255, under the image acquisition parametersdescribed below.

The structured carrier 24 preferably has an effective open area of atleast 15 percent, more preferably the structured carrier has aneffective open area of at least 20 percent, even more preferably, thestructured carrier has an effective open area of at least 25 percent,and most preferably the structured carrier has an effective open area ofat least 30 percent.

A method to determine effective aperture size and open area is describedin the method section.

5.7.2 Manufacturing Techniques

Suitable materials and structures for use as the structured carrier mayinclude apertured nonwoven webs, apertured films, apertured formedfilms, scrims, woven webs, scrim, netting, macroporous thin foams,composites of the aforementioned materials, and the like. There are anumber of manufacturing techniques which may be used to manufacture thestructured carrier 24. For example, the structured carrier 24 may be anonwoven web of fibres spunbonded, carded, wet-laid, meltblown,hydroentangled, combinations or composite laminates of the above, or thelike. Preferred structured carriers 24 include a carded/cardedcomposite, hydroentangled over a wire forming screen and thermallyair-through bonded by means well known to those skilled in the nonwovensart and hydroentanglement of fibrous webs.

5.7.3 Surface Treatment

The structured carrier 24 of the present invention may comprise asurface finish reducing the surface free energy of at least a part ofthe surface of the structured carrier and hence rendering this part ofthe surface even more hydrophobic and eventually oleophobic.

The structured may comprise hydrophobicity gradients in a directionparallel to the major surfaces of the structured carrier to provideindividual liquid handling properties in different regions of thestructured carrier. The structured carrier may also comprise ahydrophobicity gradient in a direction perpendicular to the majorsurfaces of the structured carrier in order to enhance liquid transferthrough the structured carrier.

At least a part of the surface, and in particular of the surface facingthe wearer during use, of the structured carrier 24 of the presentinvention may comprise a surface coating such as a thin fluorocarbonpolymer film. Suitable techniques to obtain such a surface coating arewell known in the art and are described for example in European patentapplication No. 98116895.8, in WO 97/42356 (Gleason) and in W096/00548(Ouellette). Another suitable surface treatment is a silicone releasecoating from Dow Corning of Midland, MI. available as Syl-Off 7677 towhich a cross-linker available as Syl-Off 7048 is added in proportionsby weight of 100 parts to 10 parts, respectively. Another suitablesurface treatment is a coating of a UV curable silicone comprising ablend of two silicones commercially available from General ElectricCompany, Silicone Products Division, of Waterford, N.Y., under thedesignations UV 9300 and UV 9380C-D1, in proportions by weight of 100parts to 2.5 parts, respectively. Another suitable treatments includefibre finishs available from Fibervisions of Varde, Denmark, under thedesignations T190 and T198, a fiber finish available from Schill andSeilacher of Böblingen, Germany, under the designation Silastol FC1760,a melt-in additive available from the Minnesota Mining And ManufacturingCompany, of St. Paul, Minn., USA. Other suitable treatment materialsinclude, but are not limited to, fluorinated materials such asfluoropolymers (e.g., polytetrafluoroethylene (PTFE), commerciallyavailable under the trade name TEFLON®) and chlorofluoropQlymers. Othermaterials which may prove suitable for providing regions of reducedsurface energy include Petrolatum, latexes, paraffins, and the like.

The structured carrier 24 of the present invention may compriseshydrophobic and oleophobic polymers. Processes to manufacture suchpolymers and articles therefrom is well known in the art and aredescribed for example in U.S. Pat. No. 3, 870,767 (Grimaud).

Optionally, the structured carrier of the present invention may betreated by modulated plasma glow discharge treatments as described inEuropean patent application No. 98116895.8 (D'Agostino et al., P&G caseCM1893FQ) and European patent application No. 98116894.1 (D'Agostino,P&G case CM1894FQ).

5.7.4 Skin Care Composition

The outer surface of the structured carrier may comprise an effectiveamount of a skin care composition which is semi-solid or solid at 20° C.and which is partially transferable to the wearer's skin. In preferredembodiment of the absorbent article of the present invention, theabsorbent article additionally comprises an skin care composition whichis at least partially transferable to the skin of the user during theintended use. Preferably, such an oil-containing composition ispositioned on a user facing surface of the absorbent article. Theoil-containing composition may also be deployed in such a way that it isonly released at the time of intended use such as beingmicroencapsulated.

Skin care compositions suitable for the absorbent article of the presentinvention are described for example in W096/16682 (Roe et al.).

Preferably, the skin care compositions suitable for the absorbentarticle of the present invention have a melting profile such that theyare relatively immobile and localised regarding their positioning withinthe absorbent article at room temperature, are transferable to the userat body temperature, and yet are not completely liquid under extremestorage conditions. Importantly, the skin care compositions of thepresent invention are easily transferable to the skin by way of normalcontact, user motion, and/or body heat.

The skin care compositions suitable for the absorbent article of thepresent invention are solid, or more often semisolid, at 20° C.,i.e. atambient temperatures. By “semisolid” it is meant that the skin carecomposition has a rheology typical of pseudoplastic or plastic fluids.When no shear is applied, the skin care compositions can have theappearance of a semi-solid but can be made to flow as the shear rate isincreased. This is due to the fact that, while the skin care compositioncontains primarily solid components, it also includes some minor liquidcomponents.

The skin care compositions suitable for the absorbent article of thepresent invention are at least semi-solid at room temperature tominimise skin care composition migration. In addition, the skin carecompositions preferably have a final melting point (100% liquid) abovepotential “stressful” storage conditions that can be greater than 45° C.

Specifically, the skin care compositions suitable for the absorbentarticle of the present invention should have the following melt profile:

Characteristic Preferred Range Most Preferred % liquid at room temp (20°C.)  2-50  3-25 % liquid at body temp (37° C.) 25-95 30-90 final meltingpoint (° C.) >=38 >=45

By being solid or semisolid at ambient temperatures, these skin carecompositions do not have a tendency to flow and migrate into theinterior of the absorbent article to which they are applied. This meansless skin care composition is required for imparting desirabletherapeutic or protective coating benefits.

When applied to the user facing surface of absorbent article of thepresent invention, the skin care compositions suitable for the absorbentarticle of the present invention are transferable to the user's skin bynormal contact, user motion, and/or body heat.

A preferred embodiment of the absorbent article of the present inventioncontains an effective amount of an skin care composition. As usedherein, the term “effective amount of an skin care composition coating”refers to an amount of a particular skin care composition which, whenapplied to a diaper structured carrier, will be effective in fulfillingtheir protective, therapeutic, or cosmetic intention. Of course, theeffective amount of a skin care composition coating will depend, to alarge extent, on the particular skin care composition used.

The skin care compositions suitable for the absorbent article of thepresent invention comprise: (1) an emollient(s); (2) an immobilisingagent(s) for the emollient; (3) optionally a hydrophilic surfactant(s);and (4) other optional components.

The viscosity of the formulated skin care compositions, includingemollient, immobilising agent, and optional components should be as highas possible to keep the skin care composition from flowing into theinterior of the absorbent article. Unfortunately, high viscosities canalso lead to skin care compositions that are difficult to apply withoutprocessing problems. Therefore, a balance must be achieved so theviscosities are high enough to keep the skin care compositions localisedon the user facing surface of the absorbent article, but not so high asto cause processing problems. Suitable viscosities for the skin carecompositions will typically range from about 5 to about 200 centipoises,preferably from about 15 to about 100 centipoises, measured at 60° C.

5.7.4.1 Emollient

The key active ingredient in these skin care compositions is one or moreemollients. As used herein, an emollient is a material that softens,soothes, supples, coats, lubricates, moisturises, or cleanses the skin.An emollient typically accomplishes several of these objectives such assoothing, moisturising, and lubricating the skin. For being suitable tobe used in the absorbent article of the present invention, theseemollients have either a plastic or fluid consistency at i.e., atambient temperatures. This particular emollient consistency allows theskin care composition to impart a soft, lubricious, lotion-like feel.

Emollients useful in the absorbent article of the present invention canbe petroleum-based, fatty acid ester type, alkyl ethoxylate type, fattyacid ester ethoxylates, fatty alcohol type, polysiloxane type, ormixtures of these emollients. Suitable petroleum-based emollientsinclude those hydrocarbons, or mixtures of hydrocarbons, having chainlengths of from 16 to 32 carbon atoms. Petroleum based hydrocarbonshaving these chain lengths include mineral oil (also known as “liquidpetrolatum”) and petrolatum (also known as “mineral wax,” “petroleumjelly” and “mineral jelly”). Mineral oil usually refers to less viscousmixtures of hydrocarbons having from 16 to 20 carbon atoms. Petrolatumusually refers to more viscous mixtures of hydrocarbons having from 16to 32 carbon atoms. Petrolatum and mineral oil are particularlypreferred emollients for skin care compositions of the presentinvention.

5.7.4.2 Immobilising agent(s) for the emollient

The immobilising agent counteracts the tendency of the emollient tomigrate or flow into the absorbent article of the present invention bykeeping the emollient primarily localised on the surface of theabsorbent article to which the skin care composition is applied.

Suitable immobilising agents for the use in the absorbent article of thepresent invention can comprise a member selected from the groupconsisting of C₁₄-C₂₂ fatty alcohols, C₁₂-C₂₂ fatty acids, and C₁₂-C₂₂fatty alcohol ethoxylates having an average degree of ethoxylationranging from 2 to about 30, and mixtures thereof. Preferred immobilisingagents include C₁₆-C₁₈ fatty alcohols, most preferably selected from thegroup consisting of cetyl alcohol, stearyl alcohol, and mixturesthereof. Mixtures of cetyl alcohol and stearyl alcohol are particularlypreferred. Other preferred immobilising agents include C₁₆-C₁₈ fattyacids, most preferably selected from the group consisting of palmiticacid, stearic acid, and mixtures thereof. Mixtures of palmitic acid andstearic acid are particularly preferred. Still other preferredimmobilising agents include C₁₆-C₁₈ fatty alcohol ethoxylates having anaverage degree of ethoxylation ranging from about 5 to about 20.Preferably, the fatty alcohols, fatty acids and fatty alcohols arelinear.

5.7.4.3 Optional hydrophilic surfactant(s)

It is important that the skin care composition also be sufficientlywettable to ensure that liquids can rapidly penetrate into at least thefirst component of the absorbent article. This diminishes the likelihoodthat body exudates will flow off the skin care composition coatingrather than being drawn into at least the first component. Dependingupon the particular immobilising agent used in the skin care compositionof the present invention, an additional hydrophilic surfactant (or amixture of hydrophilic surfactants) may, or may not, be required toimprove wettability.

5.7.4.4 Other optional components

Oil-based compositions can comprise other optional components typicallypresent in emollient, creams, and skin care compositions of this type.These optional components include water, viscosity modifiers, perfumes,disinfectant antibacterial actives, pharmaceutical actives, filmformers, deodorants, opacifiers, astringents, solvents and the like. Inaddition, stabilisers can be added to enhance the shelf life of the skincare composition such as cellulose derivatives, proteins and lecithin.All of these materials are well known in the art as additives for suchformulations and can be employed in appropriate amounts in the skin carecompositions of the present invention.

5.8 Liquid Handling Structure

5.8.1 Properties

5.8.1.1 Positioning

The liquid handling structure is located between the structured carrierand the liquid storage structure. It is preferred that the liquidhandling structure be operatively associated with the structured carriersuch that fluid bodily waste acquired through the structured carrier mayenter the liquid handling structure. In some alternate embodiments, theliquid handling structure may include a leg cuff, the waistband, afaecal waste containment pocket, or the like, or may be operativelyassociated with any such features.

A portion of the liquid handling structure is positioned in the firstregion of the absorbent article and a portion of the liquid handlingstructure is positioned in the second region of the absorbent article.In preferred embodiments, at least a part of the liquid handlingstructure is located in the region of the article that is near thewearer's urethra when worn. Further, at least a part of the liquidhandling structure is preferably located in the region of the articlethat is near the wearer's anal region when worn. This helps ensure thatany waste discharged is deposited on or near the liquid handlingstructure.

5.8.1.2 Functional Properties

The liquid handling structure of the present invention preferably iscapable of accepting, storing, immobilising and retaining viscous fluidbodily waste that is accepted and stored by the absorbent article. Thesefunctions are described above in the context of the entire absorbentarticle of the present invention.

In addition, the liquid handling structure may transport viscous fluidbodily waste within the absorbent article 20 in directions generallyparallel to the plane of the backsheet 26. The transport may be active,such that capillary or other forces result in the movement of theviscous fluid bodily waste or components thereof (e.g., free water). Inother embodiments, the transport may be passive whereby viscous fluidbodily waste or components thereof move through the structure under theinfluence of externally applied forces, such as gravity, wearer pressureor wearer motion. In the case of passive transport, the liquid handlingstructure should have relatively large, interconnected channels, or thelike, such that the viscous fluid bodily waste may readily move throughthe structure with minimum energy input.

The liquid handling structure of the present invention preferably doesnot reduce the surface tension of a liquid when the liquid handlingstructure is in contact with that liquid. Where needed, it is desirableto either use intrinsically hydrophilic materials such as cellulosicfibres, polyester fibres, or the like or to treat the hydrophobicmaterials with surfactants which are not easily released into theliquid.

5.8.1.3 Structural Properties

The liquid handling structure of the present invention has a ratio ofbasis weight to uncompressed calliper of less than 100 grams per squaremeter per millimetre, i.e. the liquid handling structure has an openstructure in order to readily accept body exudates such as urine,menses, faeces, and the like. Preferably, the liquid handling structureof the present invention has a a ratio of basis weight to uncompressedcalliper of less than 90 grams per square meter per millimetre. Morepreferably, the liquid handling structure of the present invention has aa ratio of basis weight to uncompressed calliper of less than 80 gramsper square meter per millimetre. Most preferably, the liquid handlingstructure of the present invention has a a ratio of basis weight touncompressed calliper of less than 70 grams per square meter permillimetre. Liquid handling structures having a ratio of more than 100grams per square meter per millimeter may provide a sufficient opennessto readily accept high viscosity liquids such as faeces and menses.

The liquid handling structure generally has a basis weight between 5 and500 grams per square meter. Liquid handling structure having a basisweight of less than 5 g/m² will not be able to provide the desiredresiliency and compression resistance. Liquid handling structure havinga basis weight of more than 500 g/m² will add unwanted weight to theabsorbent article which may cause discomfort by the wearer.

The liquid handling structure of the present invention generally has acalliper of at least 0.5 millimetres, preferably at least 1 millimetre.While even greater callipers would provide excellent handling of bodyexudates and in particular of low-viscosity faecal material, e.g.callipers of 5.0 centimetres, such callipers would create unwanted bulkin the diaper which may cause discomfort for the wearer.

Another key property is the resiliency of the liquid handling structure29. In order to remain open, the liquid handling structure 29 must havea sufficient resiliency to withstand the forces of packaging and thoseapplied by the wearer. The term “resiliency” as used herein refers tothe percentage of recovered calliper after the liquid handling structurehas been temporarily compressed under a defined pressure. Preferably,the liquid handling structure 29 has a resiliency of at least 50% after30 seconds under an applied pressure of 1 Newton/cm², more preferably,the liquid handling structure 29 has a resiliency of at least 75% after30 seconds under an applied pressure of 1 Newton/cm², most preferably,the liquid handling structure 29 has a resiliency of at least 85% after30 seconds under an applied pressure of 1 Newton/cm².

Regardless of the makeup of the liquid handling structure, it shouldresist compression so as to maintain some significant level of capacitywhen a compressive force is applied to the liquid handling structure.Preferably, the liquid handling structure is able to maintain at leastabout 35% of its original thickness when a compressive pressure of 1Newton/cm² is applied to the structure. More preferably, the liquidhandling structure should be able to maintain at least about 50%, andmost preferably at least about 70% of its original thickness when acompressive pressure of 1 Newton/cm² is applied. Generally, in preferredembodiments, the liquid handling structure is able to maintain betweenabout 35% and 99% of its original thickness when a compressive pressureof 1 Newton/cm² is applied to the structure; More preferably, the liquidhandling structure should be able to maintain between about 50% and 95%of its original thickness when a compressive pressure of 1 Newton/cm² isapplied.

In order to not negatively impact the liquid handling of the absorbentarticle of the present invention, the liquid handling structure has asurface tension reduction value of less than 15 mN/m, preferably lessthan 12 mN/m, more preferably less than 9 mN/, even more preferably lessthan 6 mN/m, and most preferably of less than 3 mN/m according to thesurface tension reduction test defined hereinafter.

5.8.2 Structure of the Liquid Handling Structure

The liquid handling structure may be any material or structure capableof accepting, storing, and immobilising bodily exudates, as describedabove. Thus, the liquid handling structure may include a single materialor a number of materials operatively associated with each other.Further, the liquid handling structure may be integral with anotherelement of the diaper 20 or may be one or more separate elements joineddirectly or indirectly with one or more elements of the diaper 20.Embodiments are contemplated wherein the liquid handling structureincludes at least a portion of the core 28.

5.8.3 Suitable Materials

Suitable materials for use as the liquid handling structure may includelarge cell open foams, macro-porous compression resistant nonwovenhighlofts, large size particulate forms of open and closed cell foams(macro and/or microporous), highloft nonwovens, polyolefin, polystyrene,polyurethane foams or particles, structures comprising a multiplicity ofvertically oriented looped strands of fibres, liquid storagestructure-structures described above having punched holes ordepressions, and the like. (As used herein, the term “microporous”refers to materials which are capable of transporting fluids bycapillary action. The term “macroporous” refers to materials havingpores-too large to effect capillary transport of fluid, generally havingpores greater than about 0.5 mm in diameter and more specifically,having pores greater than about 1.0 mm in diameter.) One embodimentincludes a mechanical fastening loop landing element, having anuncompressed thickness of about 1.5 millimetres available as XPL-7124from the 3M Corporation of Minneapolis, MN. Another embodiment includesa 6 denier, crimped and resin-bonded nonwoven highloft having a basisweight of 110 grams per square meter and an uncompressed thickness of7.9 millimetres which is available from the Glit Company of Wrens, Ga.The liquid handling structure, or any portion thereof, may include or becoated with a lotion or other known substances to add, enhance or changethe performance or other characteristics of the element.

5.8.3.1 Sheet Of Loop Material Having a Backing

FIG. 2 shows one embodiment of a liquid handling structure 29. Generallythe liquid handling structure 29 may be a sheet of loop material 118having a backing 120 having front and rear major surfaces 123 and 124,and a multiplicity of longitudinally oriented fibres in a speciallyformed sheet of fibres 126 having generally non-deformed anchor portions127 bonded by being embedded in the backing layer 120 at spaced elongategenerally parallel bonding locations 128 that are continuous in onedirection along the front surface 123 with arcuate portions 130 of thesheet of fibres 126 projecting from the front surface 123 of the backinglayer 120 between the bonding locations 128 in continuous rows alsoextending transversely across the sheet of loop material 118. Thearcuate portions 130 of the sheet of fibres 126 have a generally uniformheight from the backing layer 120 of greater than about 0.5 millimetresand preferably greater than about 1.0 millimetres, the height of theformed sheet of fibres 126 is at least one third, and preferably onehalf to one and one half times the distance between the bondinglocations 128, the individual fibres in the sheet of fibres 126 are lessthan 25 denier (preferably in the range of 1 to 10 denier) in size, andthe sheet of fibres 126 without the backing 120 has a basis weight inthe range of 5 to 300 grams per square meter (and preferably in therange of 15 to 100 grams per square meter) measured along the firstsurface 123 to provide. sufficient open area between the fibres in thesheet of fibres 126 along the arcuate portions 130 (i.e., between about10 and 90 percent open area) to afford ready penetration of faecalmaterial into the individual fibres along the arcuate portions 130.

Suitable materials for use as the backing 120 include but are notlimited to thermoplastic films, porous films, apertured films, aperturedformed films, unapertured formed films, nonwoven webs, breathablematerials, such as breathable films, including but not limited tomicroporous films, apertured nonwoven webs and the like. The backing 120is preferably a relatively thin layer having a thickness in the range ofabout 0.00125 to 0.025 centimetres.

The fibres in the sheet of fibres 126 can be disposed in variousdirections with respect to the parallel bonding locations 128 and may ormay not be bonded together at crossover points in the arcuate portions130; can be disposed in various directions with respect to the parallelbonding locations 128 with the majority of the fibres in the sheet offibres 126 (i.e., over 80 or 90 percent) extending in directions atabout a right angle to the bonding locations 128; or all of theindividual fibres in the sheet of fibres 126 can extend in directionsgenerally at right angles to the spaced generally parallel bondinglocations 128.

To be the most effective in the handling of body exudates and inparticular low-viscosity faecal material the liquid handling structuremust have a lofted open structure. One key component of this equation isthe height of the arcuate portions 130 of the sheet of fibres 126 fromthe backing 120. As mentioned above the-arcuate portions 130 of thesheet of fibres 126 have a generally uniform height from the backing 120of greater than about 0.5 millimetres and preferably greater than about1.0 millimetres.

5.8.3.2 Formed Film

Alternatively, a non-absorbent liquid handling structure 29 may beprovided. If a non-absorbent liquid handling structure 29 is selected,it may be provided in the form of an apertured formed film meeting thecalliper requirements described above. A suitable formed film isavailable from Tredegar Corporation of Terre Haute, Indiana under thedesignation X5790. Of course, if the liquid handling structure 29 isnon-absorbent, it must be associated with a liquid storage structure 28which has adequate capacity to absorb and retain the fluids depositedthereon.

6. METHODS

Unless stated otherwise, all tests are carried out at about 22° C. +/−2°C. and at 35+/−15% relative humidity.

Unless stated otherwise, the synthetic urine used in the test methods iscommonly known as Jayco SynUrine and is available from JaycoPharmaceuticals Company of Camp Hill, Pa. The formula for the syntheticurine is: 2.0 g/: of KCl; 2.0 g/l of Na2SO4; 0.85 g/l of (NH4)H2PO4;0.15 g/l (NH4)H2PO4; 0.19 g/l of CaCl2; ad 0.23 g/l of MgCl2. All of thechemicals are of reagent grade. The pH of the synthetic Urine is in therange of 6.0 to 6.4.

6.1 Finished-Product-Acquisition Test

Referring to FIG. 3, an absorbent structure (10) is loaded with a 75 mlgush of synthetic urine at a rate of 15 ml/s using a pump (Model7520-00, supplied by Cole Parmer Instruments., Chicago, USA), from aheight of 5 cm above the sample surface. The time to absorb the urine isrecorded by a timer. The gush is repeated every 5 minutes at precisely 5minute gush intervals until the article is sufficiently loaded. Currenttest data are generated by loading four times.

The test sample, which comprises a core and includes a topsheet and abacksheet, is arranged to lie flat on a foam platform 11 within aperspex box (only base 12 of which is shown). A perspex plate 13 havinga 5 cm diameter opening substantially in its middle is placed on top ofthe sample. Synthetic urine is introduced to the sample through acylinder 14 fitted, and glued into the opening. Electrodes 15 arelocated on the lowest surface of the plate, in contact with the surfaceof the absorbent structure 10. The electrodes are connected to thetimer. Loads 16 are placed on top of the plate to simulate, for examplea baby's weight. A pressure of 50 g cm-2 (0.7 psi) is typically utilisedin this test.

As test fluid is introduced into the cylinder it typically builds up ontop of the absorbent structure thereby completing an electrical circuitbetween the electrodes. This starts the timer. The timer is stopped whenthe absorbent structure has absorbed the gush of urine, and theelectrical contact between the electrodes is broken.

The acquisition rate is defined as the gush volume absorbed (ml) perunit time (s). The acquisition rate is calculated for each gushintroduced into the sample. Of particular interest in view of thecurrent invention are the first and the last of the four gushes.

This test is primarily designed to evaluate products having an absorbentcapacity of about 300 ml to 400 ml. If products with significantlydifferent capacities should be evaluated, the settings in particular ofthe fluid volume per gush should be adjusted appropriately to about 20%of the theoretical capacity, and the deviations should be recorded.

6.2 Topsheet-Finished-Product-Wetness Test

After executing the above described Finished-Product-Acquisition testwith only two gushes and waiting for between 5 and 6 minutes, thetopsheet is carefully removed (preferably as complete as possible) fromthe rest of the product and a piece of the topsheet is cut out with theacquisition point of the Finished Product Acquisition Test beingsubstantially centred with respect to the cut-out piece. The topsheetpiece should be 200 long and 120 mm wide. Then, the wet weight of thetopsheet is measured. Finally, the topsheet is carefully dried (forexample by heating in an oven at about 60° C.) and the dry weight of thetopsheet is measured. The wetness of the topsheet is the differencebetween the wet weight and the dry weight of the topsheet.

6.3 Liquid Retention Test

The liquid retention test measures the liquid that is retained in amaterial sample that is temporarily immersed in a test liquid havingdefined surface tension. The test liquids are prepared by usingdistilled water and dissolving a suitable amount of suitable surfactantin the water.

A sample of the material having dimension of 50 mm length and 50 mmwidth is prepared and weighed. The sample is immersed in the test liquidfor about 5 minutes. After taking the sample out of the test liquid, thesample is carefully shaken so that excess liquid can run off from thesurface of the material sample.

The liquid retention of the material sample is obtained by measuring thewet weight and taking the difference between wet weight and dry weight.

6.4 Collagen Rewet Test Method

Before executing the test, the collagen film as purchased from NATURINGmbH, Weinheim, Germany, is prepared by being cut into circular sheetsof 90 mm diameter by using a sample cutter device and by equilibratingthe film in the controlled environment of the test room (see above) forat least 12 hours (tweezers are to be used for all handling of thecollagen film).

FIG. 4 shows the experimental center used for carrying out the collagenrewet test method.

At least 5 minutes, but not more than 6 minutes after the last gush ofthe above acquisition test is absorbed, the cover plate and weights areremoved, and the test sample (4100) is carefully placed flat on a labbench.

4 sheets of the pre-cut and equilibrated collagen material (4110) areweighed with at least one milligram accuracy, and then positionedcentred onto the loading point of the article, and covered by perspexplate (4120) of 90 mm diameter, and about 20 mm thickness. A weight(4130) of 15 kg is carefully added (also centred). After 30+/−2 secondsthe weight and perspex plate are carefully removed again, and thecollagen films are reweighed.

The Skin Hydration Value is the moisture pick up of the collagen film,expressed in milligrams.

6.5 Preparation of Faecal Analogues

6.5.1 Faecal Analogue A

Analogue A is a faecal material analogue made by mixing, 10 grams ofCarbopol 941 available from the B. F. Goodrich Corporation ofBrecksville, Ohio, or an equivalent acrylic polymer in 900 millilitresof distilled water. The Carpobol 941 and distilled water are weighed andmeasured separately. A 3-bladed marine-type propeller having a 2 inchdiameter paddle, (available from VWR Scientific Products Corp. ofCincinnati, Ohio, Catalogue #BR4553-64, affixed to a ⅜″ stirring shaftBR4553-52), is used to stir the distilled water. The propeller speedshould be constant at 450 rpm during mixing. The mixer should form avortex without splashing. The Carbopol is slowly sieved into the waterso that it is drawn into the vortex and mixed without forming whiteclumps, or “fish eyes”. The mixture is stirred until all of the Carbopolhas been added, and then for a period of 2 minutes thereafter. The sidesof the bowl containing the mixture should be scraped and the bowl shouldbe rotated as needed to achieve a homogeneous mixture. (The mixture willlikely be slightly cloudy with air bubbles). One hundred grams of a 1.0N volumetric NaOH solution, available from J. T. Baker Co.,Phillipsburg, N.J., is then slowly measured into the mixture and themixture is stirred until homogeneous. The mixture should become thickand clear. The mixture should be stirred for 2 minutes after theaddition of the alkali solution. The neutralised mixture should beallowed to equilibrate for at least 12 hours and should be used for theAcceptance Under Pressure test within 96 hours thereafter. Before theCarbopol mixture is Used, it should be stirred in the container at lowspeed (about 50 rpm) for about 1 minute to ensure the mixture ishomogeneous.

Analogue A should, if prepared correctly, have a shear viscosity ofabout 13000 Pascal seconds at a shear rate of 3,12 per second measuredat a temperature of between 20 and 23° C.

6.5.2 Faecal Analogue B

The test analogue (Analogue B) used in this measurement is an aqueouspolyacrylamide solution prepared as follows. Twenty-two and five-tenths(22.5 g) grams of polyacrylamide, available from Aldrich ChemicalCompany of Milwaukee, Wisconsin is mixed with a solution of 20 g of Dawndishwashing solution, available from the Procter & Gamble Company ofCincinnati, Ohio, diluted with 1000 ml distilled water. Mixing is doneusing the same propeller used in mixing Analogue A, except that thepropeller speed should be constant during mixing at about 650 rpm.Mixing is done for 30 minutes in a water bath at 180 F. The heated waterbath is removed and the mixture is stirred for an additional 30 minutes.The mixture is allowed to equilibrate for at least 12 hours and used forthe Immobilisation Under Compressed Inversion test within 96 hours.Analogue B should have a hardness value (measured as described below) ofbetween about 7.5 and about 10.5 grams. Analogue B is designed tosimulate the water suction power of actual runny faeces from breast-fedbabies. Analogue B is generally easier to accept (i.e., more mobile)than Analogue A, which makes its retention more difficult.

6.5.3 Faecal Analogue C

The test analogue C used here is an aqueous polyacrylamide solutionprepared as follows. 11.1 grams of polyacrylamide, available fromAldrich Chemical Company of Milwaukee, Wis. is mixed with a solution of4.12 grams of FeClone #4, available from SilliClone Studios, USA, and4.12 grams of FeClone #7, available from SilliClone Studios, USA,diluted with 906.5 ml distilled water. Mixing is done using the samepropeller used in mixing Analogue A, except that the propeller speedshould be constant during mixing at about 650 rpm. Mixing is done for 30minutes in a water bath at 180 F. The heated water bath is removed andthe mixture is stirred for an additional 30 minutes. The mixture isallowed to equilibrate for at least 12 hours and used for the FecalAcceptance Test within 96 hours. Analogue C should have a hardness value(measured as described below) of between about 3 and about 5 grams.

6.6 Hardness Method

Hardness is measured using a Stevens-Famell QTS-25 Texture Analyser,model 7113-5 kg, and associated software on an Intel-based machinehaving a 486 processor or higher. A ½ inch stainless steel sphericalprobe and an analogue receptacle are provided. A suitable probe is theTA18 probe available from Leonard Farnell Co. of Hatfield, England. Theanalogue receptacle can be made by cutting a 7 millilitre linear .lowdensity polyethylene scintillation vial (having an inside diameter of0.55 inches +/−0.005 inches) to about 16 millimetre length. Suitablevials are available from Kimble Glass Company of Vineland, N.J. as#58503-7 vials. The analogue receptacle is filled to the top edge(level) with the analogue (Analogue A or B, as described below) orfaeces to be tested. If a modification agent is to be evaluated, thesample is prepared via the Sample Preparation Method described below.The vial is centred under the ½ inch spherical stainless steel probe.The probe is lowered such that it just contacts the surface of theanalogue in the vial. The probe 5162 is moved downward 7 millimetres atabout 100 millimetres per minute and then stopped. The Hardness is themaximum recorded resistive force encountered by the probe on its 7millimetre stroke. (The temperature of the room and the analogue shouldbe between about 65 to 75 degrees Fahrenheit during the course of themeasurement.) For reference, Hardness has been found to relate stronglyto the complex modulus of the material, which is a combination of theviscous and elastic moduli of the material.

6.7 Trans-topsheet Capacity

Trans-topsheet capacity is measured by the following test. The apparatus839 used for this measurement is illustrated in FIG. 8. Faecal analogueA is used to measure Trans-topsheet capacity.

A hollow stainless steel cylinder 840 mounted on a plate 842 isprovided. The stainless steel cylinder 840 has a height of 7.5centimetres (2.95 inches), an inside diameter of 5.08 centimetres (2.00inches) and an outside diameter of 6.3 centimetres (2.48 inches). Thebottom of the cylinder 840 extends below the plate a distance of 3.5millimetres, and has a lip with an annular thickness of 3.5 millimetres.The lip 843 prevents the faecal material analogue, discussed below, fromleaking outside the designated test area of the sample.

Also provided is a weight 844 of 100.6 grams. The weight 844 is alsocylindrically shaped and has a diameter of 5.08 centimetres (2.0inches), so that the weight 844 fits tightly within the cylinder 840 butcan freely slide throughout the hole in the cylinder 840. Thisarrangement provides a pressure of 49.57 kilograms per square meter(0.071 pounds per square inch) and a test area of 3.142 square inches.Ifdesired, the weight 844 may have a handle 845 to allow it to be easilyinserted into and removed from the cylinder 840.

A sample 846 to be tested is provided. The sample 846 is preferably cutfrom the second region 82 of an existing diaper 20, but propheticallymay be supplied in raw material form as a laminate of the variouscomponents of the diaper 20. The sample 846 is cut to a 10.16 by 10.16centimetres (4 by 4 inch) square size. The sample 846 is taken from anyarea of the diaper 20 having the liquid storage structure 28 inside thesquare which defines the sample 846.

If the sample 846 is cut from a diaper 20, the sample should include alllayers and components of the diaper 20 from the topsheet 24 through andincluding the backsheet 26. Care must be taken when removing the sample846 from the diaper 20 not to destroy the sample 846 or cause unintendedgross deformation of the topsheet 24. The topsheet 24, or its equivalentin the diaper 20, is removed from the balance of the sample 846. Thesample 846 (without the first topsheet 24) is weighed to the nearest0.01 grams. The topsheet 24 is then carefully returned to its originalposition in the sample 846, without being joined thereto. If difficultyis encountered in removing the sample 846 from the diaper 20, or inremoving the topsheet 24 from the sample 846, the sample 846 and thesurrounding portion of the diaper 20 may be frozen prior to or aftercutting. Freezing may be accomplished using PH100-15 circuit refrigerantmade by Philips ECG, Inc. of Waitham, Mass.

The cylinder 840 is centred on the sample 846. A syringe having anopening of 5 to 6 millimetres dispenses 10 cubic centimetres of testfluid through the hole in the cylinder 840 onto the top of the sample846. The test fluid is fecal analogue A formulated as described abovehaving a zero shear viscosity between 10000 and 15000 CentiPoise. The100.6 gram weight 844 is inserted through the hole in the cylinder 840and gently placed on the test fluid for a period of 2 minutes.

After 2 minutes the weight 844 and cylinder 840 are removed from thesample 846. The topsheet 24 is removed from the sample 846 by draggingthe topsheet 24 parallel to the sample 846 and discarded. The remainderof the sample 846 is then reweighed. The trans-topsheet capacity is theincrease in weight of all layers of the sample 846 underlying thetopsheet 24 divided by the sample 846 test area of 3.142 square inches.

6.8 Acceptance Under Pressure

Acceptance Under Pressure is measured by the following test which usesthe apparatus 5139 illustrated in FIG. 5. A hollow Plexiglas cylinder5140 is provided mounted on a stainless steel plate 5142 about 9.5 mmthick. The plate 5142 is a square, about 10.16 cm×10.16 cm (about 4 in×4in.). The cylinder 5140 and plate combination has a height of 7.6centimetres (about 3.0 inches), an inside diameter of 5.08 centimetres(about 2.00 inches) and an outside diameter of 6.3 centimetres (about2.48 inches). The bottom of the cylinder 5140 extends below the plate5142 a distance of about 3.5 millimetres. The lip 5143 prevents the testfluid 5166 from leaking outside the designated test area. Two 625 gramweights 5156 are also provided, each having a diameter of 5.08 cm (about2.0 inches).

A cylindrically shaped 24.6 gram Plexiglas weight 5144 is provided. Theweight 5144 has a diameter of 5.08 centimetres (about 2.0 inches), sothat the weight 5144 fits with close tolerance within the cylinder 5140but can freely slide throughout the hole 5141 in the cylinder 5140. Thisarrangement provides a pressure of about 119 Pascals (Pa) (about 0.017pounds per square inch) and a test area of about 20.27 square cm (about3.142 square inches). If desired, the weight 5144 may have a handle 5145to allow it to be easily inserted into and removed from the cylinder5140. In such cases, the combined mass of the handle 5145 and thecylindrical weight 5144 should equal 24.6 grams.

A sample 5146 of the structure to be tested for Acceptance UnderPressure properties is provided. The sample 5146 may be cut from anexisting diaper or may be constructed from material which has not beenformed into a diaper. The sample 5146 includes the entire structureintended for use in an article or the entire structure of the article tobe evaluated, including the top layer 5161. (In order to measure theAcceptance Under Pressure performance of discrete acceptance elements,as described in the Acceptance Element section above, the AcceptanceUnder Pressure test is performed using the standard storage element 5147in place of any underlying structure or layers. The standard storageelement 5147 used herein includes a 10.16 cm (4 inch) square 1.6 mmthick aluminium plate having a pattern of 153 regularly spaced 4.3 mmdiameter holes 5168, as shown in FIG. 7. The holes are arranged suchthat there are about 26 holes per square inch.) The sample 5146 shouldbe cut into a square measuring 10.16 centimetres by 10.16 centimetres(about 4 inches by 4 inches).

Five layers of a high basis weight blotter 5149 measuring 10.16 cm×10.16cm (4 inches×4 inches) are provided. The top layer 5161 of the sample5146 is removed and the remaining components, or layers, of the sample5146 (if there are multiple components or layers) and the five sheets ofblotter material 5149 are weighed to the nearest 0.01 grams. Thus, ifthe sample 5146 is being taken from a diaper, the layers of the diapersuch as topsheets, secondary topsheets, acquisition layers, liquidstorage structures etc., should be separated prior to weighing. (In somecases, a single layer may comprise two or more permanently bondedcomponents.) In so doing, care must be taken not to destroy the sample5146 or cause unintended gross deformation of any parts of the sample5146. The layers of the sample 5146 may be frozen to aid theirseparation from adjacent layers of the sample 5146. Freezing may beaccomplished using PH100-15 circuit refrigerant made by Philips ECG,Inc. of Waltham, Mass.

The sample 5146 should be reassembled as originally configured on top of5 stacked layers of blotter material 5149 with the side of the sample5146 intended to face the wearer oriented facing up and away from theblotter material 5149. The blotter material 5149 is preferablyfiltration grade paper, available from Ahlstrom Filtration, Inc. of Mt.Holly Springs, Pa. as #632-025, having a basis weight of about 90 gramsper square meter.

The combined assembly of the sample 5146 and the blotter material 5149is centred on the work surface 5164 of a Stevens-Farnell QTS-25 Model7113-5 kg Texture Analyser 5160 (available from Leonard Famell Co. ofHatfield, England), under the probe 5162. A suitable probe 5162 is a 100cm flat-ended cylindrical aluminium extension rod “QTSM3100” availablefrom the Leonard Farnell Co. of Hatfield England. The cylinder 5140 iscentred on the sample 5146. The two 625 gram weights 5156 are placed onopposite corners (diagonally) of the plate 5142 to stabilise it. Asyringe having an opening of about 4 to 6 millimetres is used todispense approximately 10 cubic centimetres of viscous fluid bodilywaste analogue 5166 (Analogue C as described above) through the hole5141 in the cylinder 5140 onto the top of the sample 5146.

Once the proper amount of viscous fluid bodily waste analogue 5166,Analogue C, has been measured into the cylinder 5140, the 24.6 gramweight 5144 is inserted slowly and gently into the hole 5140 in thecylinder 5140 until it rests on the surface of the analogue. The TextureAnalyser 5160 is activated so the probe 5162 depresses the cylindricalweight 5144 at a rate of 10 millimetres per minute until a resistingforce of about 1.42N (144.6 grams of force) is reached. The TextureAnalyser 5160 is set to stop the downward stroke once the resistanceforce of 1.42N (144.6 grams of force) is reached. The recorder is set totrigger at a resistive force of 0.049N (5 grams of force) therebydefining starting point so. The maximum resisting force of 1.42N (144.6grams of force) corresponds to an applied pressure of 700 Pascals (0.1pounds per square inch). Once a resistive force of 1.42N (144.6 grams offorce) is reached, the probe 5162 is retracted to its starting position.

The weight 5144 is removed from the cylinder 5140, and then the cylinder5140 is removed from the surface of the sample 5146, taking care not todrip any Analogue C remaining in the cylinder 5140 onto the sample. Thetop layer 5161 of the sample 5146 is then removed from the underlyinglayer(s) of the sample 5146 by dragging the top layer 5161 parallel tothe surface of the underlying layers, if possible. For certainstructures where the top layer 5161 is difficult to remove by draggingparallel to the underlying layers, the top layer 5161 may be peeled orlifted away from the underlying layers of sample 5146. If the sample5146 comprises only a single layer, the standard acceptance element,described below, is utilised as the top layer 5161 of the sample 5146.The underlying layers of the sample 5146 and the blotter material 5149are then weighed.

The acceptance under load A_(L) of the sample 5146 equals the increasein combined weight of the underlying layer(s) of the sample 5146 and theblotter material 5149 caused by the test Analogue C penetrating throughthe top surface layer of the sample 5146 per work W performed (inmillijoules) on a unit area basis. The work Wis calculated byintegrating the force F(s)resisting the probe on its downward strokefrom the starting point at s₀ over the total distance travelled untilthe maximum force of 1.42N (144.6 grams of force) is registered ats_(max). The unit work is calculated using the following equation:W = ∫_(s₀)^(s_(max))F(s)  s

6.9 Storage Under Pressure

Storage Under Pressure is measured using the same apparatus 5139described above and illustrated in FIG. 5. The hollow cylinder 5140,weight 5144, and 625 g weights 5156 described in the Acceptance UnderPressure test above are provided. A sample 5146 of the structure to betested for Storage Under Pressure properties is also provided. Again,the sample 5146 may be cut from an existing diaper 20 or may beconstructed from material which has not been formed into a diaper. Thesample 5146 should include the entire structure intended for use in anarticle or the entire structure of the article to be evaluated. (Inorder to measure the Storage Under Pressure performance of discretestorage elements, as described in the Storage Element section above, theStorage Under Pressure test is performed using the standard acceptanceelement in place of any overlying structure or layers. The standardacceptance element 150 is a stainless-steel wire cloth Type 304(Standard Grade) 16×16 mesh, available as #9226T45 from McMaster CarrSupply Company of Chicago, Ill.) The sample 5146 should be cut into asquare measuring 10.16 centimetres by 10.16 centimetres (about 4 inchesby 4 inches).

Five layers of a high basis weight blotter 5149 (identical to thatdescribed in the Acceptance Under Pressure test above) measuring 4inches×4 inches are provided. The top layer 5161 of the sample 5146 isremoved and the remaining components, or layers, of the sample 5146 (ifthere are multiple components or layers) and the five sheets of blottermaterial 5149 are weighed to the nearest 0.01 grams. Thus, if the sample5146 is being taken from a diaper, the top layer 5161 of the diaper,such as the topsheet, should be separated from the sample 5146 prior toweighing. In so doing, care should be taken not to destroy the sample5146 or cause unintended gross deformation of the elements of sample5146. The layers of the sample 5146 may be frozen, as described above,to aid their separation from adjacent layers of the sample 5146.

The sample 5146 should be reassembled as originally configured on top offive stacked sheets of blotter material 5149 with the side intended toface the wearer oriented facing up and away from the blotter material5149. The combined assembly of the sample 5146 and the blotter material5149 is centred on the work surface 5164 of the Texture Analyser 5160(described above), under the probe 5162. The cylinder 5140 is centred onthe sample 5146. The two 625 gram weights 5156 are placed on diagonallyopposite corners of the plate 5142 to stabilise it. A syringe having anopening of about 4 to 6 millimetres is used to dispense 10 cubiccentimetres Analogue C (as described above) through the hole in thecylinder 5140 onto the top of the sample 5146. The 24.6 gram weight 5144is inserted into the hole 5141 in the cylinder 5140 and the TextureAnalyser 5160 is activated with the probe 5162 depressing thecylindrical weight 5144 at a rate of 10 millimetres per minute until aresisting force of 1.42N (144.6 grams of force) is reached. (The maximumresisting force of 1.42N (144.6 grams of force) corresponds to anapplied pressure of 700 Pascals or 0.1 pounds per square inch). Once theresisting force of 1.42N (144.6 grams of force) is reached, the probe5162 is retracted to its starting position.

The weight 5144 is removed from the cylinder 5140, and then the cylinder5140 and weights 5156, are removed from the surface of the sample 5146,taking care not to drip any Analogue C remaining in the cylinder 5140onto the sample. The sample 5146 is then removed from the work surface5164 of the Texture Analyser 5160 by dragging the sample 5146 parallelto the work surface 5164, if possible. For certain structures where thetop layer 5161 is difficult to remove by dragging parallel to theunderlying layers, the top layer 5161 may be peeled or lifted away fromthe underlying layers of sample 5146. The sample 5146 and the blotter5149 are then weighed. The amount of test Analogue C 5166 stored equalsthe increase in combined weight of the underlying layers of the sample5146 and the blotter 5149 caused by the test Analogue C penetrating intothe sample 5146 on a unit area basis.

6.10 Immobilisation and Retention Under Compressed Inversion

To measure Immobilisation Under Compressed Inversion and Retention UnderCompressed Inversion, a cylinder 5140 is mounted on plate 5142 as shownin FIG. 5. The cylinder 5140 has a height of 7.5 centimetres (about 2.95inches), an inside diameter of 5.08 centimetres (about 2.00 inches) andan outside diameter of 6.3 centimetres (about 2.48 inches). The hollowcylinder 5140 and plate 5142 are identical to those used in theAcceptance Under Pressure and Storage Under Pressure tests describedabove, with the exception that the plate does not have the “lip” 5143 onthe bottom, and that both the cylinder 5140 and the plate 5142 are madeof stainless steel. The stainless steel cylinder 5140 and plate 5142have a combined weight of about 1170 grams.

The sample 5146 of the structure to be tested is provided and the toplayer 5161, if included in the sample 5146, is removed. The remainingunderlying layers of the sample 5146 and the five layers of blottermaterial 5149 are assembled and weighed. The top layer 5161 is thenplaced on top of this assembly. The sample 5146 may also be made frommaterials that have not been made into a structure. The combinedassembly of the sample 5146 to be tested and blotter 5149 is placed on abenchtop 5165. (In order to measure the Immobilisation Under CompressedInversion and Retention Under Compressed Inversion performance ofdiscrete immobilisation and retention elements, as described in theImmobilisation Element section above, the Immobilisation UnderCompressed Inversion test is performed using the standard acceptanceelement in place of any top layer 5161. All underlying layers areincluded in this evaluation.) A syringe having an opening of about 4 to6 millimetres is used to dispense 10 cubic centimetres of test analoguethrough the hole in the cylinder 5140 onto the top of the sample 5146.

The test analogue (Analogue B) is allowed to penetrate the sample 5146under gravitational force for 3 minutes. The cylinder 5140 is thenremoved from the surface of the sample 5146 and the entire sample 5146is weighed. The top layer 5161 of the sample 5146 is then removed fromthe underlying layers of the sample 5146 by lifting the top layer 5161vertically from the surface of the underlying layers and allowing anyexcess Analogue B to drain back into the lower layers. The assembly ofthe remainder of sample 5146 and the blotter material 5149 is thenweighed. This provides a measure of the net quantity of Analogue B Q_(B)imbibed by the structure during the loading step of this test. Thesample 5146 is then reassembled, including the top surface layer 5161.Three layers of the 4 inch square blotter material 5149 are provided andweighed. A standard storage element 5147 is provided and placed on topof the three layers of blotter material 5149. The reassembled sample5146 is inverted onto the assembly of the standard storage element 5147and the three layers of blotter material 5149. (The standard storageelement 5147 includes a 4 inch square 1.6 millimetre thick aluminiumplate having a pattern of 153 regularly spaced 4.3 millimetre diameterholes 5168, as shown in FIG. 7. The holes are arranged such that thereare approximately 26 holes per square inch.)

A 16 pound, 16 square inch weight 5158 (corresponding to a 7000 Pascalpressure, or 1.0 psi) is then gently placed on the surface of the sample5146 which is facing away from the standard storage element 5147. Theweight 5158 is removed after three minutes, and the sample 5146 isreoriented so that the side insulted by the test Analogue B is facingup. The top layer 5161 is removed and the weight of the remaining layersof sample 5146 and the five layers of blotter material are measured andrecorded. The sample's Retention Under Compressed Inversion R_(CI) iscalculated as the actual net amount of test Analogue B present in theunderlying layers of the structure after the inversion cycle.

Immobilisation Under Compressed Inversion I_(CI) is calculated as thepercentage of the test Analogue B that penetrated the structure (i.e.,passed through the surface layer into the underlying layers of thesample) during the loading step which remains in the underlying layersof the structure after the inversion step. The equation for determiningImmobilisation Under Compressed Inversion is as follows:$I_{CI} = \frac{R_{CI}}{Q_{B}}$

6.11 Surface tension measurement

All measurements were done on a commercially available digitaltensiometer, Type K 10 T of Krüss GmbH, Germany, applying the well knownring method. Thereby, the force to pull a circular ring of platinumimmersed into the test liquid upwards is monitored, and whileconsidering gravity and buoyancy the surface tension is determined,expressed in N/cm.

All glassware and the platinum ring is cleaned with isopropanol anddeionized water and then dried in a drying oven at 50° C. Shortly beforeperforming the measurement, the glassware is further cleaned and driedby using a Bunsen burner flame, and then cooled down to 37° C. in adesiccator.

All measurements are done at 37° C., by heating the test solution andthe sample holder to 37° C.

The glass beaker of the equipment is filled with 25 ml (+/−5 ml) testsolution (preferably directly from the main reservoir without using antransfer tool like a burette) and placed in the sample holder. Then theplatinum ring is heated until red heat in the flame of a Bunsen burnerand immediately put into the ring holding device.

The equipment is then initiated to automatically perform themeasurement, i.e. immersing and pulling of the ring at a constant speedwhile measuring the forces. The result can be directly read from thedisplay of the equipment.

Unless otherwise noted, each measurement is replicated 3 times, and theresults are averaged.

6.12 Surface Tension Reduction Measurement

The surface tension reduction test of the present invention is intendedto measure the impact of one of the components of the absorbent articleof the present invention on the surface tension of an acquired liquid.

All glassware and the platinum ring is cleaned with isopropanol anddeionized water and then dried in a drying oven at 50° C. Shortly beforeperforming the measurement, the glassware is further cleaned and driedby using a Bunsen burner flame, and then cooled down to 37° C. in adesiccator.

At the beginning of the test, the surface tension of 40 ml of deionizedwater is measured via the above surface tension test. Then, 3 samples ofthe component to be tested are immersed into the 40 ml of deionizedwater. The sample of the component shall weigh about 0.05 gram. Theconfiguration of the sample should resemble as closely as possible theconfiguration of the component in the absorbent article, in particularin terms of surface area accessible to the acquired liquid. In case, thesample of the components weighs less than 0.05 gram the amount of testliquid has to be adjusted accordingly. After 5 minutes, the sample iscompletely removed from the test liquid. The surface tension of theremaining liquid is measured three times.

The surface tension reduction of the tested component of the absorbentarticle is the difference between the initial surface tension and thefinal surface tension of the deionized water.

6.13 Method to determine effective aperture size and open area of astructured carrier

The effective aperture size and effective open area are determined bythe following procedure using the image analysis described below. Theprocedure has three principal steps: image acquisition, i.e., obtainingrepresentative images of areas on the surface of the structured carrier24; image measurement, i.e., measuring the percentage open area of animage and of individual apertures and their perimeters; and dataanalysis, i.e., exporting the percentage open area, individual aperturearea, and perimeter measurements to a spreadsheet where frequencydistributions, sum of area distributions, and hydraulic radiuscomputations are made.

An image analysis system having a frame grabber board, microscope,camera and image analysis software is utilised. A model DT2855 framegrabber board available from Data Translation of Marlboro, Mass. isprovided. A VH5900 monitor microscope, a video camera, having aVH50 lenswith a contact type illumination head available from the Keyence Companyof Fair Lawn, N.J., USA are also provided and used to acquire an imageto be saved to computer file. The Keyence microscope acquires the imageand the frame grabber board converts the analogue signal of this imageinto computer readable digital format. The image is saved to computerfile and measured using suitable software such as the Optimas ImageAnalysis software, version 3.1, available from the BioScan Company ofEdmaons, Wash. In order to use the Optimas Image Analysis software, thecomputer should have Windows software, version 3.0 or later, availablefrom the Microsoft Corporation of Redmond, Wash. And also have a CPU atleast equivalent to the Intel 80386. Any suitable desk top PC may beused, with a 486 DX33 type PC having been found to be particularlysuitable. Images being saved to and recalled from file were displayed ona Sony Trinitron monitor model PVM-1343MO with a final displaymagnification of about 50×.

The image acquisition step, noted above requires 10 different regionsfrom a representative structured carrier 24 sample of a particular typeof diaper 20 or from sample material to be tested. Each region isrectangular, measuring about 5.8 millimetres by 4.2 millimetres. Thesample is placed on a black mat board to increase the contrast betweenthe apertures and the portion of the sample which defines the apertures.The mean grey level and standard deviation of the black mat board were16 and 4, respectively.

Images are acquired with room lights off using the Keyence monitormicroscope mounted on a copystand directly above the sample. The Keyencelight source illuminating the sample is adjusted and monitored with theOptimas software to measure the mean grey level and standard deviationof a 0.3 density wedge on a Kodak Grey Scale available from EastmanKodak Company of Rochester, N.Y. The control of Keyence light source isadjusted so that the mean grey level of the illuminated wedge is 111+1and the standard deviation is 10+1. All images were acquired during asingle time period, and the Keyence light source is monitored bymeasuring the mean grey level and standard deviation of the wedgethroughout the image acquisition process.

In measuring an individual aperture, only the effective aperture size isof interest. Measuring the effective aperture size quantifies theaperture size intended to contribute to the porosity of the structuredcarrier 24, and account for contributions of fibres and fibre bundleswhich traverse an area intended to be an aperture. An effective apertureis any hole through the structured carrier 24 having a grey level lessthan or equal to 18 using image acquisition parameters as describedherein. Thus, an intended aperture may be divided into plural effectiveapertures by traverse fibres.

The image analysis software is calibrated in millimetres by a rulerimage acquired from the sample images. A 3 by 3 pixel averaging filterfound in the Optimas 3.1 Image menu is applied to each saved image toreduce noise. The apertures are detected in the grey level range of 0through 18. An aperture which is not fully contained within the 5.8 by4.2 viewing area is not considered in the individual area and perimetermeasurements. Therefore, area and perimeter averages and distributionsare not affected by apertures which are not wholly contained within thefield of view.

However, individual apertures which could not be fully viewed in theimage are included in the percentage open area calculation. Thisdifference occurs because the percent open area is simply the image ofpixel ratios from 0 through 18 to the total number of pixels in theimage. Areas having a grey level 19 or greater were not counted in theopen area calculation.

The percentage open area for the average of 10 images for eachstructured carrier 24 is measured using the Optimas Image Analysissoftware. The percentage open area is defined as the ratio of the numberof pixels having a grey level from 0 through 18 to the total number ofpixels for the image. The percentage open area is measured for eachimage representing one particular region from a structured carriersample. The percentage open area from each of the 10 individual imagesis then averaged to yield a percentage open area for the entire sample.

The data analysis is conducted by an Excel spreadsheet, also availablefrom the Microsoft Corporation of Redmond, Washington. The Excelspreadsheet organised the percentage open area, aperture area, andaperture perimeter measurements obtained from the Optimas software.Sample averages and standard deviations, size and frequencydistributions of individual aperture areas and hydraulic radiuscomputations (area divided by perimeter) for individual apertures areobtained using the spreadsheet.

Distributions of individual aperture area are also computed using theExcel spreadsheet. The apertures are sorted into bins of certain sizeranges. The number of aperture areas falling into certain size ranges ofinterest is determined as well as the sum of the areas within eachrange. The ranges are set in increments of 0.05 square millimetres.These areas are expressed as a percentage of the total open area of thesample. The frequency and sum of the area distributions are obtained bycombining individual aperture measurements from all 10 images for eachsample.

What is claimed is:
 1. A disposable absorbent article having atransverse centerline, a first region, and a second region, said firstregion being positioned forward of said transverse centerline, saidfirst region coming into contact with the front waist of the wearerduring use, said second region being positioned backward of saidtransverse centerline, said second region coming into contact with theback waist of the wearer during use, said disposable absorbent articlecomprising a liquid pervious structured carrier, a liquid imperviousbacksheet at least partially peripherally joined to said structuredcarrier, a liquid storage structure positioned intermediate saidtopsheet and said backsheet, and a liquid handling structure positionedintermediate said topsheet and said liquid storage structure, a portionof said liquid handling structure being positioned in said first region,a portion of said liquid handling structure being positioned in saidsecond region, characterised in that said absorbent article has atopsheet wetness value of less than 120 milligrams according to theTopsheet-Finished-Product-Wetness Test Method disclosed herein and saiddisposable absorbent article has a front region Storage Under Pressureof at least 800 grams per square meter according to the Storage UnderPressure Test disclosed herein.
 2. A disposable absorbent articleaccording to claim 1 wherein said disposable absorbent article has afront region total product acquisition performance of more than 3.75ml/s in the first gush and of more than 0.5 ml/s in the fourth gush. 3.A disposable absorbent article according to claim 1 wherein saiddisposable absorbent article has a front region Skin Hydration value ofless 120 mg according to the Collagen Rewet Test Method defined herein.4. A disposable absorbent article according to claim 1 wherein saiddisposable absorbent article has a front region immobilisation undercompressed inversion of at least 70% according to Immobilisation UnderCompressed Inversion Test disclosed herein.
 5. A disposable absorbentarticle according to claim 4 wherein said disposable absorbent articlehas a front region retention under compressed inversion of least 7.5grams according to the Retention Under Compressed Inversion Testdisclosed herein.
 6. A disposable absorbent article according to claim 1wherein said disposable absorbent article has a back region StorageUnder Pressure of at least 0.5 grams per square metre according to theStorage Under Pressure Test disclosed herein.
 7. A disposable absorbentarticle according to claim 4 wherein said disposable absorbent articlehas a back region immobilisation under compressed inversion of at least70% according to the Immobilisation Under Compressed Inversion Testdisclosed herein.
 8. A disposable absorbent article according to claim 7wherein said disposable absorbent article has a back region retentionunder compressed inversion of at least 7.5 g according to the RetentionUnder Compressed Inversion Test disclosed herein.
 9. A disposableabsorbent article according to claim 1 wherein said structured carriercomprises a plurality of apertures having a size of at least 0.2 mm².10. A disposable absorbent article according to claim 1 wherein saidstructured carrier has a open area of more than 12%.
 11. A disposableabsorbent article according to claim 1 wherein said liquid handlingstructure has a compression resistance of at least 70% under an appliedpressure of 1 Newton per square centimeter.
 12. The disposable absorbentarticle according to claim 1 wherein said liquid handling structure hasa resiliency of at least 50% after 30 seconds under an applied pressureof 1 Newton per square centimetre.
 13. A disposable absorbent articleaccording to claim 1 wherein said liquid handling structure has a basisweight to uncompressed caliper ratio of less than 100 grams per squaremeter per millimeter.
 14. A disposable absorbent article according toclaim 1 wherein said liquid handling structure comprises a backing and asheet of fibres, said sheet of fibres having anchor portions in saidbacking at spaced bonding locations and having arcuate portions of saidsheet projecting from said backing between bonding locations.